Compendium Specialty Series: Surgical Views

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Surgical Treatment of Urethral Sphincter Mechanism Incompetence in Female Dogs ❯❯ Mary A. McLoughlin, DVM, MS, DACVS ❯❯ Dennis J. Chew, DVM, DACVIMa The Ohio State University

At a Glance Urethral Sphincter Mechanism Incompetence Page 360

Diagnosis Page 361

Surgical Treatment of Urethral Sphincter Mechanism Incompetence Page 362

Medical Management of Urethral Sphincter Mechanism Incompetence in Female Dogs Page 364

Future Directions in Treatment Page 373

aDr. Chew discloses that he has

received financial support from Bayer Animal Health and Nestlé Purina PetCare Company.

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Abstract: Urinary incontinence—loss of voluntary control over the retention and expulsion of urine—is a common medical problem in small animal patients. Incontinence occurs when pressure within the bladder exceeds urethral pressure. Incontinence may result from a variety of etiologies, including congenital anatomic abnormalities of the lower urinary and reproductive systems (ureter, bladder, bladder neck, urethra, vagina, vestibule) as well as neurologic, neoplastic, infectious, and inflammatory diseases.

Urethral Sphincter Mechanism Incompetence Urethral sphincter mechanism incompetence (USMI), also referred to as idiopathic incon­ tinence, spay incontinence, and hormoneresponsive incontinence, is the most common and important cause of acquired urinary incontinence in adult female dogs.1–4 USMI is largely a condition of spayed dogs, but in some breeds, such as greater Swiss mountain dogs, soft-coated wheaten terriers, Doberman pinschers, and giant schnauzers, incontinence may precede ovariohysterectomy (OVH). Congenital USMI has also been recognized as a cause of incontinence in juvenile dogs and is frequently associated with other anatomic malformations, such as ureteral ectopia and ureteroceles.1–4 Approximately 20% of female dogs have been reported to develop some degree of USMI after OVH performed between the first and second heat cycles.5 In dogs spayed before first estrus, the incidence is reported to be 9.7%.5 The incidence of incontinence may be as high as 30% in large-breed female dogs (>20 kg); in some breeds, including boxer, Doberman pinscher, rottweiler, Old

English sheepdog, and giant schnauzer, it is even higher.1,2,4,6–8 Urinary in­continence is most often reported within 3 years of spaying.1–4 There is no reported difference in the incidence of incontinence between dogs in which ovariectomy alone was performed and dogs that underwent OVH. Decreases in maximal urethral closure pressure (MUCP) and functional urethral length predictably occur during the first 12 to 18 months after neutering, resulting in a caudal shift of the urethral pressure profile and deterioration of urethral closure function. It is speculated that the decline in MUCP continues with advancing age, further contributing to the development of incontinence in later life.1,2,7,8 The term urethral sphincter mechanism incompetence was first suggested to de­scribe weakness of the “urinary sphincter” despite the fact that no true anatomic sphincter exists at the bladder neck or proximal urethra. The smooth muscle of the proximal urethra is continuous with the detrusor muscle layer of the bladder trigone.1 Therefore, congenital anatomic abnormalities affecting the ureters, bladder neck, and proximal urethra can impair development of the normal smooth

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muscle architecture in this region, contributing to incontinence.1–4 Varying amounts of fibrovascular tissue located throughout the length of the bladder neck and urethra may also play a role in maintenance of continence.1–3 Caudal displacement of the bladder into the pelvic canal is recognized as pelvic bladder syn­ drome.9,10 The hallmark radiographic appearance of a pelvic bladder shows abnormal elongation of the bladder, persistent caudal displacement of the bladder and bladder neck into the pelvic canal on distention, an indistinct or blunted vesicourethral junction, and a shortened urethra.9,10 Shortening of the urethra reduces exposure of the bladder neck and proximal urethral wall to the intraabdominal pressure that acts as an external occluding force.1,2,4,6–8 Abnormally short urethras are frequently noted in dogs with USMI. Pelvic bladder has been reported in male and female dogs with and without urinary incontinence.9,10 The significance of pelvic bladder and its role in the pathophysiology of USMI are not completely understood, but pelvic bladder is thought to be a contributing factor in patients with USMI.9,10 USMI is considered to be a multifactorial disorder, and the specific etiopathogenesis remains unclear.1–4,6–8 USMI in dogs has been likened to stress incontinence diagnosed in women after pregnancy, childbirth, or menopause. In women, sudden increases in abdominal pressure from actions such as coughing, sneezing, and laughing can result in loss of bladder control.1,2,6,7 Varying degrees of urinary incontinence have been reported in dogs with USMI. Most owners report leakage of urine when the dog is recumbent or sleeping. Increased periods of incontinence have also been reported in dogs after strenuous exercise, excitement, and steroid administration. In our experience, swimming and eating snow can also lead to increased incontinence in dogs.

Diagnosis The diagnosis of USMI is established by ruling out structural and functional abnormalities of the urinary and reproductive systems in patients that are neurologically normal. Physical examination findings are frequently unremarkable. Specific examination of the vulva and perivulvar region is necessary to

Surgical Views is a collaborative series between the American College of Veterinary Surgeons (ACVS) and Compendium. Upcoming topics in this series include cystoscopy and cystoscopic stone removal, vacuumassisted wound closure, and conventional foreign object removal. All Surgical Views articles are peer-reviewed by ACVS diplomates. To locate a diplomate, ACVS has an online directory that includes practice setting, species emphasis, and research interests (acvs.org/VeterinaryProfessionals/FindaSurgeon).

assess vulvar conformation and degree of vulvar recession. Perivulvar dermatitis and hyperpigmentation of the perivulvar skin secondary to chronic incontinence are frequently noted in dogs with USMI. Cystocentesis to collect a urine sample for complete urinalysis and bacteriologic culture is a critical first step in the diagnosis and management of patients with urinary incontinence. Infection, inflammation, uroliths, or neoplasia of the lower urinary system can result in loss of continence. If a urinary tract infection exists, treatment with appropriate antibiotic therapy for 14 to 21 days, followed by reevaluation of a urine culture 5 to 7 days after the completion of antibiotic therapy, should precede other diagnostic procedures. Abdominal radiography may detect radio­ dense urinary calculi or caudal displacement of the urinary bladder into the pelvic canal. Contrast radiography (e.g., retrograde vaginocystography) and contrast-enhanced computed tomography can enable more specific evaluation of the vestibule, vagina, and lower urinary and reproductive structures, including detailed information regarding the location of the bladder neck, urethral length, ureteral size, location of ureteral orifices, bladder wall thickness or irregularity, and presence of small uroliths. Uroendoscopy is useful to evaluate the luminal surfaces of the lower urinary and reproductive systems under magnification.

QuickNotes Cystocentesis to collect a urine sample is a critical first step in the diagnosis and management of patients with urinary incontinence.

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The surgical procedures reported in the veterinary literature to improve USMI in small animal patients have all been adapted and modified from procedures performed on women with diagnosed stress incontinence.

FIGURE 1

Colposuspension

Illustration by Tim Voit

Description

Illustration of colposuspension. Cranial traction is applied to the bladder and uterine body remnant. The vagina is exposed on either side of the urethra immediately cranial to the pubis. Nonabsorbable monofilament sutures are placed between the prepubic tendon and the seromuscular layer of the vagina, positioning the bladder neck cranially into the abdomen.

QuickNotes Surgical treatment is typically reserved for patients in which appropriate medical management has failed or is not possible.

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Anatomic abnormalities such as ureteral ectopia, ureterocele, and structural defects of the trigone and urethra can be definitively diagnosed with this method of imaging. Specific diagnostic confirmation of USMI is made based on the results of urodynamic studies, including a urethral pressure profile and leak point pressure. Patients with USMI have a decreased MUCP and leak point pressure compared with continent dogs.6,7,11–13

Surgical Treatment of Urethral Sphincter Mechanism Incompetence

Colposuspension uses the placement of sutures between the vagina and the prepubic tendon to create urethral resistance to urine outflow. This procedure results in cranial advancement and repositioning of the bladder neck and proximal urethra, exposing these structures to intraabdominal pressure. In addition, the urethra, cradled by the vagina, is positioned over the edge of the pelvic brim, which applies additional external compression (Figure 1). Colposuspension is the surgical procedure most commonly performed to treat spayed dogs with USMI. Colposuspension alone was reported to be curative in approximately 50% of patients; in approximately 40% of the remaining patients, continence was improved.1,2,6–8 A recent study evaluated the immediate urodynamic response to colposuspension in normal beagles.6 Leak point pressures were significantly increased, while MUCPs were decreased. Urethral length was assessed using measurements from vaginourethrograms and urethral pressure profiles and was determined to be slightly increased based on evaluation of lateral radiographs. Urodynamic studies indicated that the total profile length and the functional profile length were significantly increased.6 The long-term effects of colposuspension also have been examined in female dogs with USMI.7 Two months after colposuspension, 12 of 22 female dogs achieved complete continence. However, only three dogs remained completely continent 12 months after surgery. When medical therapy was instituted after surgery, an additional eight dogs regained complete urinary continence and nine were improved.7

Medical therapy (Box 1) is the first line of treatment for dogs with USMI. Surgical treatment of USMI is typically reserved for patients in which appropriate medical management has failed, that have adverse reactions to recommended medications, or that have medical conditions precluding the use of medical therapies. The goal of surgical treatment of USMI is to increase urethral resistance to the outflow of urine. To accomplish this, surgical procedures focus on correcting caudal displacement of the bladder neck to (1) increase intraabdominal forces and provide improved MUCP within the urethra (colposuspension, urethropexy, and urethral Technique lengthening), (2) increase urethral resistance With the patient in dorsal recumbency, clip and by reducing the diameter of the urethral aseptically prepare the ventral abdomen from lumen (urethropexy and submucosal collagen the xyphoid over the pubis, including the peri­ implants), and (3) improve functional urethral vulvar region. Aseptically pass an appropriatelength (colposuspension, urethral lengthening). size balloon-tip urethral catheter transurethrally

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into the bladder. Perform a caudal midline celiotomy from the umbilicus, extending over the cranial aspect of the pubis, and identify and isolate the insertion of the rectus abdominis muscles and prepubic tendon (Figure 2). Expose the bladder, proximal urethra, and uterus or uterine body remnant. If the patient is intact, OVH is performed at this point. Place a stay suture through the apex of the bladder for traction and manipulation and an Allis tissue forceps on the uterine body remnant for cranial traction. A peritoneal reflection forming the vesicogenital pouch exists between the dorsal aspect of the pelvic urethra and the ventral aspect of the vagina, tethering these structures together (Figure 3). This intimate anatomic association allows cranial traction of the uterine body remnant and vagina to result in cranial movement of the bladder neck and urethra. With cranial traction applied to the bladder and uterine body remnant, use a curved mosquito hemostat or right-angled forceps to bluntly dissect a small window through the periurethral fascia along each side of the urethra immediately cranial to the pubic brim, exposing the vagina dorsal to the urethra (Figure 4). Take care to avoid excessive dissection and disruption of the neurovascular supply to the vagina and urethra, positioned dorsolaterally within the pelvic canal. Identify the lateral wall of the vagina and grasp it with atraumatic forceps positioned on each side of the urethra. Based on the size of the patient, pre-place one or two 2-0 nonabsorbable monofilament sutures through the seromuscular layer of the vaginal wall on each side of the urethra and through the prepubic tendon, entering and exiting lateral to the insertion of the rectus abdominis muscle (Figure 5). Firm cranial traction on both the bladder and uterine remnant is needed to achieve cranial positioning while these sutures are tied on either side of the urethra. Insert a mosquito hemostat between the ventral aspect of the urethra and the pelvic brim to ensure that the urethra is not completely obstructed (Figure 6). Close the abdomen in a routine manner.

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Postoperative Care A urethral catheter with a closed urinary collection system should be maintained for 24 hours after surgery. Transient dysuria and stranguria due to urethral inflammation and partial urethral obstruction can occur after catheter removal. Complete urethral obstruction after colposuspension is rare. If complete urethral obstruction occurs, replacement of the urethral catheter for an additional 24 to 36 hours and administration of an NSAID are indicated. Attempts to manually express Compendium: Continuing Education for Veterinarians®

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Medical Management of Urethral Sphincter Mechanism Incompetence in Female Dogs Urethral sphincter mechanism incompetence (USMI) may be fully, partially, or transiently responsive to medical management.

QuickNotes Medical therapy is the first line of treatment for dogs with urethral sphincter mechanism incompetence.

α-Adrenergic Agonists Phenylpropanolamine (PPA; 1.0 to 1.5 mg/kg PO bid to tid) effectively controls incontinence in approximately 74% to 92% of dogs with USMI by stimulating α-adrenergic receptors in the urethra, increasing urethral tone. Many patients that are not completely continent following administration of PPA have improved continence.1,2,11–13,a In one study, more than half of the dogs that failed to respond when treated with the standard formulation of PPA became continent when treated with a sustained-release formulation (75-mg capsules; dose based on body weight).a The ability of PPA to control USMI decreases over time in some dogs. Not all α-adrenergic agonists are as effective as PPA in controlling incontinence. A recent study showed PPA to be more effective than pseudoephedrine.13 Minimal adverse effects (restlessness, mild behavioral changes) associated with PPA administration have been reported in some dogs. Dogs with systemic hypertension or clinically relevant cardiac or renal disease should not be treated with α-adrenergic agonists.11–13,a Estrogens Estrogens have also been shown to be effective in controlling USMI by increasing the number or sensitivity of α-adrenergic receptors in the urethra. Estrogens may have other, less well understood effects, including increased urethral tone arising from vascular changes and reduction in circulating concentrations of follicle-stimulating hormone (FSH) and luteinizing hormone (LH).1–4,11,b Estriol increases urethral resistance in sexually intact and spayed female dogs without urinary incontinence.

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Estrogen therapy alone improves incontinence resulting from USMI in approximately 65% to 83% of treated dogs.1,2,b Diethylstilbestrol (DES; 0.5 to 1.0 mg/dog [0.02 mg/kg]), which is available from veterinary compounding pharmacies, is often effective in reducing incontinence attributed to USMI. A maximal induction dose of 1 mg/dog is given for 3 to 7 days; the dose is then decreased to every other day and then to the lowest dose that will maintain continence. Some dogs cannot tolerate DES at the doses required to maintain continence without manifesting clinical signs of estrus. Conjugated estrogens such as Premarin (Wyeth Pharmaceuticals, Philadelphia) are more readily available than DES and can be administered at 20 μg/kg every 4 days as an alternative therapy. Bone marrow toxicity is a potential adverse effect of estrogen therapy, but treatment with low doses of DES or conjugated estrogens appears to be safe. Intermittent low-dose maintenance with DES or conjugated estrogen to control incontinence may be preferred by owners over multiple daily doses of PPA, despite the fact that PPA is often more effective. In some patients with refractory incontinence, DES can be administered simultaneously with PPA to achieve a synergistic response that may effectively control incontinence. Other Therapies Detrusor instability or hyperactive bladder may contribute to incontinence in some dogs with USMI. A therapeutic trial with anticholinergic agonists (e.g., oxybutynin, flavoxate) to relax spasms of the detrusor muscle may be warranted. Oxybutynin (0.2 mg/kg PO q8–12h) and flavoxate (100 to 200 mg PO q8h) have been effective in the treatment of potential detrusor instability in dogs.

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Box 1

Treatment with gonadotropin-releasing hormone (GnRH) analogues was recently reported to result in complete continence in more than half of dogs with USMI in which traditional medical therapies failed.c,d An average of 253 days of continence was observed in seven dogs that became fully continent with a GnRH analogue as the sole treatment. An additional five dogs that had partial improvement with GnRH analogue treatment became fully continent when PPA was also administered. Treatment with GnRH analogues reduces the concentrations of FSH and LH that develop after OVH in dogs.e Increased concentrations of FSH and LH may play a role in development of USMI in susceptible dogs. However, MUCP does not appear to be directly related to circulating concentrations of FSH or LH.e Treatment with leuprolide, a GnRH analogue, did not increase MUCP in dogs with USMI that regained urinary continence.c,d Receptors for GnRH, FSH, and LH have been demonstrated in various regions and densities in the canine urethra and bladder. With a success rate of 71%, long-acting GnRH analogues are effective as a first-line treatment for USMI, but this rate is lower than that achieved with PPA.

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Bacon NJ, Oni O, White RAS. Treatment of urethral sphincter mechanism incompetence in 11 bitches with a sustained-release formulation of phenylpropanolamine hydrochloride. Vet Rec 2002;151(13):373-376. b Angioletti A, DeFrancesco I, Vergottini M, Battocchio ML. Urinary incontinence after spaying in the bitch: incidence and oestrogen-therapy. Vet Res Commun 2004;28(Suppl 1):153-155. c Reichler IM, Jöchle W, Piché CA, et al. Effect of long acting GnRH analog or placebo on plasma LH/FSH, urethral pressure profiles and clinical signs of urinary incontinence due to sphincter mechanism incompetence in bitches. Theriogenology 2006;66(5):1227-1236. d Reichler IM, Barth A, Piché CA, et al. Urodynamic parameters and plasma LH/FSH in spayed beagle bitches before and 8 weeks after GnRH depot analogue treatment. Theriogenology 2006;66:2127-2136. e Reichler IM, Pfeiffer E, Piché CA, et al. Changes in plasma gonadotropin concentration and urethral closure pressure in the bitch during the 12 months following ovariectomy. Theriogenology 2004;62(8):1391-1402. a

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FIGURE 2

FIGURE 3

QuickNotes Colposuspension is the surgical procedure most commonly performed to treat spayed dogs with urethral sphincter mechanism incompetence.

Surgical exposure of bladder and urethra for colposuspension. The abdominal incision extends over the pubis, exposing the insertion of the rectus abdominis muscle and prepubic tendon (arrows). FIGURE 4

Dissection of the periurethral fascia on either side of the urethra immediately cranial to the pubis exposes the dorsally positioned vagina.

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The bladder is reflected caudally, demonstrating the vesicovaginal fold (arrow) between the dorsal aspect of the urethra and the vagina. Cranial traction of the vagina facilitates repositioning of the bladder neck cranially into the abdomen. FIGURE 5

Placement of colposuspension sutures. Nonabsorbable monofilament sutures are pre-placed between the prepubic tendon and the seromuscular layer of the vagina on either side of the urethra.

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the bladder to void its contents may cause patient discomfort. Persistent complete urethral obstruction that does not respond to appropriate conservative treatment over a period of 3 to 5 days after surgery may require removal of the colposuspension sutures between the vaginal wall and prepubic tendon.

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Urethropexy

Description

Urethropexy is an alternative to colposuspension that is aimed at restoring the bladder neck and proximal urethra to an intraabdominal position while simultaneously increasing resistance to urine flow by reducing the diameter of the urethral lumen.14,15 Cystourethropexy was initially reported in 10 female dogs diagnosed with USMI and pelvic bladder. The results of surgery alone were considered excellent in two dogs, and urethropexy combined with medical therapy (phenylpropanolamine [PPA]) resulted in marked improvement in an additional six dogs. One dog did not improve with surgery.14 A later study reported the results of treatment of 100 female dogs with urethropexy for incontinence due to USMI.15 Surgery alone led to complete control of incontinence in 56 dogs and improvement of continence in 27 dogs. Of the other 17 dogs, nine failed to respond and eight showed initial improvement but later relapsed. Nine of these 17 dogs underwent a second urethropexy procedure, resulting in complete continence in six dogs and improvement in three. Postoperative complications were observed in 21 dogs, including increased frequency of urination (14 dogs), dysuria (six), and anuria (three).15 As with other procedures intended to increase tension within the urethral wall, transient or persistent dysuria as a result of partial urethral obstruction and failure to improve continence were the most common complications noted in both studies.14,15

Technique Position the patient in dorsal recumbency and clip and aseptically prepare the ventral abdomen. Perform a caudal midline celiotomy from the umbilicus, extending over the cranial aspect of the pubis. Expose the bladder, urethra, and uterine body remnant and place a stay suture through the apex of the bladder for cranial traction. Using blunt dissection, clear the periurethral fat from the ventral aspect of the bladder neck and pelvic urethra. Pre-place six to 10 horizontal mattress sutures bilaterally using a 2-0 nonabsorbable monofilament suture material. The sutures should enter the abdominal cavity, passing full thickness through the ventral abdominal wall, including the rectus fascia. They should Compendium: Continuing Education for Veterinarians®

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FIGURE 6

to pass a urethral catheter after surgery may be difficult and traumatic to the surgical site within the urethra and should be avoided if at all possible. Administration of an NSAID for 7 to 10 days after surgery is indicated to reduce discomfort and soft tissue swelling.

Urethral Lengthening

Description

Cranial traction is applied to the uterine body remnant while the pre-placed sutures are tied to complete the colposuspension. A mosquito hemostat is gently inserted between the pubis and the urethra to ensure that the urethra is not completely obstructed.

QuickNotes A significantly short urethra prohibits cranial movement of the bladder neck into the abdominal cavity, eliminating the ability to use some surgical procedures.

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Urethral lengthening has been used to treat congenital USMI in cats and dogs with a notably shortened urethra resulting in pelvic displacement of the bladder neck. A significantly short urethra (urethral hypoplasia) prohibits cranial movement of the bladder neck into the abdominal cavity, eliminating the ability to use surgical procedures such as colposuspension, urethropexy, and urethral slings to treat USMI. Reconstruction of the bladder neck and the use of ventrally based bladder tube flaps have been reported to taper the bladder neck, thereby elongating the proximal urethra. Excellent or good results were reported in seven of eight cats treated with this technique, and a good outcome was described in one dog.16,17 Urethral lengthening using bladder wall flaps has also been described for treatment of urinary incontinence in people. This technique may warrant further consideration with expanded clinical evaluation for the treatment of USMI in small animals with pelvic bladder.

then pass through the seromuscular layer of the urethra in a horizontal mattress pattern at either the nine or three o’clock position in the transverse section without penetrating the urethral lumen. The sutures then exit from the abdominal cavity through the abdominal wall, Technique including the rectus fascia, on the same side Position the patient in dorsal recumbency and (Figure 7). The two most caudal sutures on clip and aseptically prepare the ventral abdoeither side of the urethra are engaged through men. Perform a caudal midline celiotomy from the prepubic tendon as they enter and exit the umbilicus, extending over the cranial aspect the abdomen. Tighten and tie the pre-placed of the pubis. Expose the bladder, urethra, and sutures from caudal to cranial on each side of uterine body remnant. Make a ventral cystothe urethra. Close the abdomen routinely.14,15 tomy incision, extending into the proximal urethra, and create two V-shaped flaps in the Postoperative Care ventral aspect of the ventral bladder wall, using Some degree of stranguria and dysuria will the caudal extent of the incision in the proximal occur after surgery due to the increased outflow urethra as the point of both V flaps (Figure 8). resistance created within the urethral lumen. The widest portion of each V flap is located at Stranguria may persist for several weeks after the level of the ureteral orifices, at the tip of surgery. The patient’s voiding patterns should the trigone. Use 4-0 monofilament absorbable be observed daily for the first few days after sutures in a continuous or interrupted pattern surgery to be sure a small stream of urine is to primarily close the linear defect created in passed with each voiding effort. Complete the ventral wall of the bladder neck and proxiurethral obstruction is uncommon. Attempts mal urethra, thereby decreasing the diameter of

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the bladder neck lumen and elongating the proximal urethra. The initial descriptions of this procedure recommended suturing the bladder flaps to each other to prevent a loss in bladder capacity.17 Alternatively, resection of the bladder flaps makes the surgical procedure and closure much simpler, and the resultant loss of bladder capacity is usually inconsequential. Due to the tremendous regenerative capacity of the bladder, presurgical vesicular capacity is restored within a few weeks to months after surgery.

Postoperative Care Increased frequency of urination and stranguria are the most commonly anticipated ad­verse effects after reconstructive procedures to lengthen the urethra. Stranguria may be noted for several weeks. Avoid placement of a urethral catheter unless complete urethral obstruction occurs. Intermittent cystocentesis can be performed over a 24- to 36-hour period, and administration of an NSAID is indicated to reduce soft tissue inflammation of the lower urinary tract. Acepromazine administered at a low dose (0.01 to 0.025 mg/kg SC, IM, or IV q8h) may help relax the urethra, reducing stranguria and facilitating urine flow.

Urethral Slings

Description

Urethral sling procedures using seromuscular flaps created from the bladder wall or a synthetic material passed transpelvically through the obturator foramen have been combined with colposuspension to provide additional external compression of the pelvic urethra, increasing resistance to urine flow.18,19 These procedures are technically more difficult to perform. The reported outcomes are similar to those of colposuspension alone. It remains unclear whether there is an advantage to the use of a combined procedure.18 The modified sling urethroplasty procedure creates external compression at the vesicourethral junction by wrapping two seromuscular flaps created from the bladder neck region around the proximal urethra to increase resistance to urine flow.19

Technique Perform a colposuspension as previously de­scribed. Following colposuspension, make a 2- to 2.5-cm ventral midline incision through the seromuscular layer of the bladder neck, extending to the junction of the proximal urethra. Raise two rectangular seromuscular pedicle flaps with a caudal base from the ventral surface of the bladder neck region (Figure 9). These flaps should be between 4 and 10 mm in width, depending on the size of the patient. Place a 4-0 absorbable monofilament stay suture through the free end of each flap. Pass the flaps around each side of the proximal urethra and secure them on the dorsal aspect to provide compression at the vesicourethral junction.19 Primarily close the remaining seromuscular defect on the ventral bladder neck with a simple continuous or interrupted pattern using 4-0 absorbable monofilament sutures. Remove the urethral catheter to permit complete closure of this defect. If necessary, additional sutures can be placed dorsally in the sutured flaps to adjust the tension of the sling. Compression provided by the sling should be such that gentle digital pressure on the bladder is necessary to exceed the urethral pressure that permits urine flow.19 Close the abdomen in a routine manner.

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Minimally Invasive Urethral Bulking

Collagen Injection Technique Position the patient in right lateral recumbency under general anesthesia. Clip and aseptically prepare the vulva and perivulvar region. A 19or 14-French rigid cystoscope with a 30° angle is used for uroendoscopy and the injection procedure. Endoscopy is performed using a sterile fluid infusion to create a clear visual

Illustration of urethropexy procedure. Six to 10 sutures are pre-placed bilaterally between the body wall incision and the seromuscular layer of the urethra in a horizontal mattress pattern at either the three or nine o’clock position when viewed transversely. The most caudal sutures on either side engage the prepubic tendon as they enter and exit the abdomen. FIGURE 8

Illustration by Tim Voit

If the results of medical or surgical treatment of USMI are incomplete or unsatisfactory, endoscopic submucosal implantation of urethral bulking agents such as polytetrafluoroethylene (Teflon) or medical-grade collagen can be performed to create intraluminal resistance to urine outflow.20–22 Successful urethral bulking with submucosal collagen has been reported in women and dogs.21,22 Collagen products are commonly used in people to correct defects of the skin and soft tissues. A specific collagen product for urologic use (Contingen, Bard Urological, Covington, GA) has been commercially developed and approved for use in humans. This product is composed of highly purified bovine dermal collagen that is cross-linked with glutaraldehyde and dispersed in phosphate-buffered saline. The collagen component is composed of approximately 95% type I collagen and 5% or less type III collagen. This product is packaged in a sterile 2.5-mL syringe for single use. Collagen has a higher degree of biocompatibility compared with other products previously reported for urethral bulking (e.g., polytetrafluoroethylene). Initial reports showed a control rate (complete continence) of 53% for USMI treated with one or two series of submucosal injections of collagen. This rate improved to 75% when PPA was administered to dogs in which collagen injections provided inadequate urinary control.21 More recently, a success rate of 68% was reported in 40 female dogs with USMI treated with submucosal collagen injections.22 Some dogs may require a second series of collagen injections if incontinence is uncontrolled or relapses. Repeat injection procedures are usually easier to complete because the previous urethral bulking site is readily identified and augmented.

Illustration by Tim Voit

FIGURE 7

Description

Illustration of urethral lengthening using the bladder-flap reconstruction technique. A midline cystotomy incision is made extending to the proximal urethra. Two V-shaped full-thickness flaps are created in the ventral bladder wall (dashed lines). The point of each V is the caudal extent of the incision in the proximal urethra. The widest portion is at the level of the ureteral orifices. The flaps can be excised with little consequence to bladder capacity. Primary closure of the linear incision in the ventral wall of the bladder neck and proximal urethra reduces the luminal diameter of the bladder neck, thereby elongating the proximal urethra.

field. Mucosal hemorrhage can be controlled with the infusion of cold fluids. An assistant with sterile gloves should prepare the collagen and injection device. Perform a complete evaluation of the lower urinary and reproductive structures to rule out anatomic causes of urinary incontinence before injecting the collagen. Position the tip

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FIGURE 9

FIGURE 10

FIGURE 11

Endoscopic view of submucosal collagen injection. The injection needle is passed through the biopsy channel of the cystoscope and positioned immediately below the mucosal layer of the urethra distal to the vesicourethral junction.

Endoscopic view of completed submucosal collagen injections. Visual occlusion of the urethral lumen.

Illustration by Tim Voit

of the cystoscope within the proximal urethra to visualize the vesicourethral junction, and aseptically pass the injection device through the biopsy channel of the cystoscope until the beveled needle end is visible in the optical field. The recommended site for collagen injection is approximately 1.5 to 2 cm caudal to the vesicourethral junction. Position the cystoscope to facilitate insertion of the beveled tip of the injection device immediately below the urethral mucosa into the submucosal layer.

Slowly inject the collagen, watching for immediate elevation of the urethral mucosa to create a mounding effect (Figure 10). If the needle is positioned too deep, there is minimal to no intraluminal deformation of the urethral mucosa. The collagen is commonly injected at three to four sites in a circle. The amount of collagen injected at each site is determined visually. Injection of excessive collagen at any given site can result in mucosal disruption and leakage of collagen from the site. The procedure is considered complete when the injection sites appose one another, achieving visual obstruction of the urethral lumen (Figure 11). Patients should be continent immediately after this procedure. Dogs with moderate to severe inflammation or urinary tract infection may experience some minor incontinence until the infection/inflammation is resolved medically. If incontinence persists after the initial collagen injections, this procedure can be repeated, enhancing the previously injected sites. Administration of PPA has been shown to further enhance control of urinary continence after collagen injection. Complete urinary outflow obstruction has not been reported in dogs. Follow-up endoscopic examinations have uniformly demonstrated that the submucosal collagen deposits can remain visually unchanged for years. Relapse of incontinence after prolonged successful control with collagen injections may be related to absorption of the phosphate buffer component of the collagen preparation.

Illustration of the modified urethral sling procedure. A ventral midline incision is made through the seromuscular layer of the bladder neck and proximal urethra. Two rectangular seromuscular pedicle flaps are elevated from the ventral surface of the bladder neck region. The flaps are passed around each side of the vesicourethral junction and secured on the dorsal aspect, providing external compression of the bladder neck. Primary closure of the seromuscular defect on the ventral bladder neck tapers the bladder neck and elongates the proximal urethra.

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Future Directions in Treatment Recognizing that no medical or surgical treatments of female dogs with USMI have been uniformly successful, current investigations are focusing on the practical use of gonadotropin-releasing hormone analogues as a single therapy or in combination with other medical or surgical treatments (Box 1). In addition, work has begun to evaluate the efficacy of a percutaneously controlled static hydraulic urethral sphincter in dogs.23 This system consists of a doughnut-shaped silicone vascular occluder attached to a subcutaneous fluid injection port. The luminal diameter of the occluder can be adjusted by the infusion of small volumes of saline through the injection port. The occluder is surgically placed around the bladder neck to provide external compression, preventing passive urine outflow, and the degree of occlusion is adjusted until optimal

References

1. Gregory SP. Developments in the understanding of the pathophysiology of urethral sphincter mechanism incompetence in the bitch. Br Vet J 1994;150:135-150. 2. Holt PE. Importance of urethral length, bladder neck position and vestibulovaginal stenosis in sphincter mechanism incompetence in the incontinent bitch. Res Vet Science 1985;39:364-372. 3. McLoughlin MA. Management of urinary incontinence. Proc BSAVA Symp 2004. 4. Hoelzler MG, Lidbetter DA. Surgical management of urinary incontinence. Vet Clin North Am Small Anim Pract 2004 (34):1057-1073. 5. Stöcklin-Gautschi NM, Hässig M, Reichler IM, et al. The relationship of urinary incontinence to early spaying in bitches. J Reprod Fertil Suppl 2001:57:233-236. 6. Fowler JD, Rawlings CA, Mahaffey MB, et al. Immediate urodynamic and anatomic response to colposuspension in female beagles. Am J Vet Res 2000;61:1353-1357. 7. Rawlings CA, Barsanti JA, Mahaffey MB, Bement S. Evaluation of colposuspension for treatment of incontinence in spayed female dogs. JAVMA 2001;219(6):770-775. 8. Gregory SP, Holt PE. The immediate effect of colposuspension on resting and stressed urethral pressure profiles in anesthetized incontinent bitches. Vet Surg 1994;23:330-340. 9. Mahaffey MB, Barsanti JA, Barber DL, Crowell WA. Pelvic bladder in dogs without urinary incontinence. JAVMA 1984;184(12): 1477-1479. 10. Adams WM, DiBartola SP. Radiographic and clinical features of pelvic bladder in the dog. JAVMA 1983;182(11):1212-1217. 11. Rosen AE, Ross L. Diagnosis and pharmacological management of disorders of urinary incontinence in the dog. Compend Cont Educ Pract Vet 1981;3:601-610. 12. Richter KP, Ling GV. Clinical response and urethral pressure profile changes after phenylpropanolamine in dogs with primary sphincter mechanism incompetence. JAVMA 1985;187:605-611. 13. Byron JK, March PA, Chew DJ, DiBartola SP. Effect of phenylpropanolamine and pseudoephedrine on the urethral pressure profile and continence scores of incontinent female dogs. J Vet Intern Med 2007;21(1):47-53.

control (i.e., the patient can void urine without obstruction and retain urine without incontinence) is achieved.23

Conclusion Surgical treatment of USMI is focused on dogs in which appropriate medical therapies have failed or medical conditions prevent the use of medical treatment. Surgery or minimally invasive procedures such as collagen implantation may provide further control of continence in some difficult cases.

SURGICAL VIDEO

To see a video of collagen injection, visit CompendiumVet.com.

14. Massat BJ, Gregory CR, Ling GV, et al. Cystourethropexy to correct refractory urinary incontinence due to urethral sphincter mechanism incompetence preliminary results in ten bitches. Vet Surg 1993;22(4):260-268. 15. White RN. Urethropexy for the management of urethral sphincter mechanism incompetence in the bitch. J Small Anim Pract 2001;42:481-486. 16. Holt PE. Surgical management of congenital urethral sphincter mechanism incompetence in eight female cats and a bitch. Vet Surg 1993;22(2):98-104. 17. Fowler JD, Holmberg DL. Proximal urethral reconstruction using a distally based bladder tube flap an experimental study. Vet Surg 1987;16(2):139-145. 18. Muir P, Goldsmid SE, Bellenger CR. Management of urinary incontinence in five bitches with incompetence of the urethral sphincter mechanism by colposuspension and a modified sling urethroplasty. Vet Rec 1994;34:38-41. 19. Nickel RF, Wiegand U, Van Den Brom WE. Evaluation of a transpelvic sling procedure with and without colposuspension for treatment of female dogs with refractory urethral sphincter mechanism incompetence. Vet Surg 1998;27:94-104. 20. Arnold S, Jaeger P, DiBartola S, et al. Treatment of urinary incontinence in dogs by endoscopic injection of Teflon. JAVMA 1989;195:1369-1374. 21. Arnold S, Hubler M, Lott-Stolz G, Rusch P. Treatment of urinary incontinence in bitches by endoscopic injection of glutaraldehyde cross-linked collagen. J Small Anim Pract 1996;37:163-168. 22. Barth A, Reichler IM, Hubler M, et al. Evaluation of long-term effects of endoscopic injection of collagen into the urethral submucosa for treatment of urethral sphincter incompetence in female dogs: 40 cases (1993-2000). JAVMA 2005;226(1):73-76. 23. Adin CA, Farese JP, Cross AR, et al. Urodynamic effects of a percutaneously controlled static hydraulic urethral sphincter in canine cadavers. Am J Vet Res 2004;65(3):283-288.

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Section Namee

At a Glance Risk Factors for Gastric Dilatation–Volvulus Page 60

Overview of the Veress Needle and Hasson Technique for Obtaining Abdominal Access Page 60

Laparoscopic-Assisted Gastropexy Page 61

Laparoscopic Gastropexy Page 63

a

Dr. Rawlings discloses that he has received financial support from Biovision, Covidien, Ellman International, Endoscopic Support Services, and Karl Storz Veterinary Endoscopy.

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Laparoscopic-Assisted and Laparoscopic Prophylactic Gastropexy: Indications and Techniques ❯❯ Jeffrey J. Runge, DVM University of Pennsylvania

❯❯ Philipp Mayhew, BVM&S, MRCVS, DACVS Columbia River Veterinary Specialists Vancouver, Washington

❯❯ Clarence A. Rawlings, DVM, PhD, DACVSa The University of Georgia

G

astric dilatation–volvulus (GDV) is open surgical gastropexy techniques have a syndrome characterized by rapid been described: tube, circumcostal, belt accumulation of gas or food in the loop, muscular flap, gastrocolopexy, and stomach, increased intragastric pressure incisional. Because of the high mortality and wall tension, and rotation of the rate associated with the development of stomach about its long axis. Gastric dis- GDV, these procedures may be used protention unleashes a series of potentially phylactically in dogs that have not had GDV lethal pathophysiologic events, the most but are considered to be at high risk.8,9 important of which are compression of Studies have indicated that a prophylacthe portal and caudal vena caval venous tic gastropexy can result in a twofold to blood flow, gastric necrosis, tissue aci- 30-fold reduction in lifetime mortality assodosis, cardiac arrhythmia, disseminated ciated with GDV for rottweilers and Great intravascular coagulation, and hypoten- Danes, respectively.10 sive and cardiogenic shock.1 For dogs Recent advances in veterinary medicine that develop GDV, surgical correction have included a move toward more miniis strongly recommended. Among those dogs, mortality remains high (15% to TO LEARN MORE 33%), even with aggressive resuscitative management.2–5 A gastropexy is the creation of a permanent adhesion between the gastric antrum and the adjacent right body wall. Failure to perform a gastropexy at the time of surgery for GDV correction results in a >50% recurrence rate,4 whereas performing a prophylactic gastropexy during corrective surgery for GDV decreases the recurrence rate by 4% to 10%.4,6,7 As a result, gastropexy is now considered the standard of care.4 Several

Compendium: Continuing Education for Veterinarians® | February 2009 | CompendiumVet.com

For a detailed description of abdominal access using a Veress needle or the Hasson technique, see the August 2008 Surgical Views article, “Canine Laparoscopic and LaparoscopicAssisted Ovariohysterectomy and Ovariectomy.” This article is available at CompendiumVet.com.


Dechra_USE.qxp:1

1/16/09

10:24 AM

Page 1

What do dogs who take VETORYL (trilostane) have in common? ®

Results like these.

Prior to VETO RYL treatment

Effective treatment for Cushing’s syndrome is now FDA approved. You now have easy access to the most powerful ^LHWVU PU [OL ÄNO[ HNHPUZ[ JHUPUL *\ZOPUN»Z syndrome. VETORYL Capsules are the only licensed treatment available for both pituitary-dependent and adrenal-dependent hyperadrenocorticism.

treatment Following 3 months of with VETORYL

VETORYL Capsules contain the active ingredient trilostane, which blocks the excessive production of cortisol. Daily administration of VETORYL can greatly reduce the clinical signs associated with Cushing’s syndrome, enhancing the quality of life for both dog and owner. For more information, visit www.VETORYL.com. Contact your local veterinary distributor to order VETORYL Capsules today!

Following 9 months of treatment with VETO RYL

(trilostane)

Photographs courtesy of Carlos Melian, DVM, PhD

VETORYL is a trademark of Dechra Ltd. ©2009, Dechra Ltd. NADA 141-291, Approved by FDA (Z ^P[O HSS KY\NZ ZPKL LMMLJ[Z TH` VJJ\Y 0U ÄLSK Z[\KPLZ [OL TVZ[ JVTTVU ZPKL LMMLJ[Z YLWVY[LK ^LYL WVVY YLK\JLK HWWL[P[L ]VTP[PUN SL[OHYN` diarrhea, and weakness. Occasionally, more serious side effects, including severe depression, hemorrhagic diarrhea, collapse, hypoadrenocortical crisis, VY HKYLUHS ULJYVZPZ Y\W[\YL TH` VJJ\Y HUK TH` YLZ\S[ PU KLH[O =,;69@3 *HWZ\SLZ HYL UV[ MVY \ZL PU KVNZ ^P[O WYPTHY` OLWH[PJ VY YLUHS KPZLHZL or in pregnant dogs. Refer to the prescribing information for complete details or visit www.VETORYL.com. VTYL0209-01-47122-CPD

See Page 60 for Product Information Summary


VETORYL Capsules (trilostane) ®

30 mg and 60 mg strengths Adrenocortical suppressant for oral use in dogs only

BRIEF SUMMARY (For Full Prescribing Information, see package insert.) CAUTION: Federal (USA) law restricts this drug to use by or on the order of a licensed veterinarian. DESCRIPTION: VETORYL is an orally active synthetic steroid analogue that blocks production of hormones produced in the adrenal cortex of dogs. INDICATIONS: VETORYL Capsules are indicated or the treatment of pituitary-dependent hyperadrenocorticism in dogs. VETORYL Capsules are indicated for the treatment of hyperadrenocorticism due to adrenocortical tumor in dogs. CONTRAINDICATIONS: The use of VETORYL Capsules is contraindicated in dogs that have demonstrated hypersensitivity to trilostane. Do not use VETORYL Capsules in animals with primary hepatic disease or renal insufficiency. Do not use in pregnant dogs. Studies conducted with trilostane in laboratory animals have shown teratogenic effects and early pregnancy loss. WARNINGS: In case of overdosage, symptomatic treatment of hypoadrenocorticism with corticosteroids, mineralocorticoids and intravenous fluids may be required. Angiotensin-converting enzyme (ACE) inhibitors should be used with caution with VETORYL Capsules, as both drugs have aldosterone-lowering effects which may be additive, impairing the patient’s ability to maintain normal electrolytes, blood volume and renal perfusion. Potassium-sparing diuretics (e.g., spironolactone) should not be used with VETORYL Capsules as both drugs have the potential to inhibit aldosterone, increasing the likelihood of hyperkalemia.

QuickNotes Predisposition to GDV has been demonstrated for several breeds.

HUMAN WARNINGS: Keep out of reach of children. Not for human use. Wash hands after use. Do not empty capsule contents and do not attempt to divide the capsules. Do not handle the capsules if pregnant or if trying to conceive. Trilostane is associated with teratogenic effects and early pregnancy loss in laboratory animals. In the event of accidental ingestion/overdose, seek medical advice immediately and take the labeled container with you. PRECAUTIONS: Hypoadrenocorticism can develop at any dose of VETORYL Capsules. A small percentage of dogs may develop corticosteroid withdrawal syndrome within 10 days of starting treatment. Mitotane (o,p’-DDD) treatment will reduce adrenal function. Experience in foreign markets suggests that when mitotane therapy is stopped, an interval of at least one month should elapse before the introduction of VETORYL Capsules. The use of VETORYL Capsules will not affect the adrenal tumor itself. Adrenalectomy should be considered as an option for cases that are good surgical candidates. ADVERSE REACTIONS: The most common adverse reactions reported are poor/reduced appetite, vomiting, lethargy/dullness, diarrhea, and weakness. Occasionally, more serious reactions including severe depression, hemorrhagic diarrhea, collapse, hypoadrenocortical crisis, or adrenal necrosis/rupture may occur, and may result in death.

(trilostane) Distributed by: Dechra Veterinary Products 7015 College Boulevard, Suite 525 Overland Park, KS 66211 www.VETORYL.com 866-933-2472 VETORYL is a trademark of Dechra Ltd. © 2009, Dechra Ltd. NADA 141-291, Approved by FDA

mally invasive procedures, and the use of laparoscopic surgery for creating a less invasive prophylactic gastropexy has been investigated. These techniques can be performed in isolation or in conjunction with surgical sterilization. Laparoscopic-assisted,11 laparoscopic,12–14 and endoscopic15 gastropexy techniques have proven successful. The clinical outcome of a reported laparoscopic-assisted gastropexy16 indicated a persistent attachment between the stomach and the body wall with few complications and effective prophylaxis against GDV development. Studies reveal that an intracorporeally sutured laparoscopic gastropexy can be performed safely and effectively and has less impact on the dog’s postoperative activity level than a laparoscopic-assisted gastropexy.13 However, the adhesion strength and long-term outcome of the intracorporeally sutured laparoscopic technique have not yet been evaluated.13 In this article, we describe the techniques for laparoscopic-assisted and laparoscopic gastropexy.

Risk Factors for Gastric Dilatation–Volvulus A breed predisposition has been demonstrated for Great Danes, German shepherds, standard poodles, Weimaraners, Saint Bernards, Gordon setters, Irish setters, bassett hounds, Airedale terriers, Irish wolfhounds, borzois, bloodhounds, Akitas, and bull mastiffs.2,3 Large,

Overview of the Veress Needle and Hasson Technique for Obtaining Abdominal Access BOX 1

The Veress needle has a blunt-tipped, spring-loaded stylet within a sharp-tipped needle. As it is advanced through the body wall, the sharp tip penetrates the abdominal musculature; once within the peritoneal cavity, the spring-loaded protective stylet is deployed, thus minimizing risk of iatrogenic organ damage when the abdominal cavity is penetrated. Peritoneal insufflation can then be performed through the needle, followed by trocar placement. The Hasson technique uses a blunt cannula in a trocar–cannula assembly that is passed through a very small incision, usually created in a subumbilical location. Once the peritoneum has been sharply penetrated, the trocar–cannula assembly is advanced into the abdomen, pointing to the right side to minimize the risk of splenic laceration. If a 5-mm telescope and instrumentation are used, a 6-mm trocar–cannula assembly should be placed first.

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Laparoscopic-Assisted Gastropexy To perform a laparoscopic-assisted gastropexy, place the dog in dorsal recumbency and clip and aseptically prepare the abdomen from the xiphoid cartilage to the brim of the pubis. Abdominal access can be obtained by use of a Veress needle or the Hasson technique (BOX 1). If the Hasson technique is used, a blunt cannula must be employed for initial port placement. If a pneumoperitoneum has already been established through the use of a Veress needle, a sharp cannula can be used for this purpose. A pneumoperitoneum is usually established with carbon dioxide, using a mechanical insufflator that allows controlled insufflation and intraabdominal pressure monitoring. The intraabdominal pressure measured with the insufflator should not be allowed to exceed 10 to 15 mm Hg while the trocars are placed; it should then be reduced to 6 to 8 mm Hg, or just sufficient to maintain an optical space, during the laparoscopic portion of the gastropexy. Place a 0° or 30° 5-mm laparoscope through the subumbilical port, just lateral to the right margin of the rectus abdominus and 3 to 5 cm caudal to the last rib (FIGURE 1). The second trocar–

FIGURE 1

QuickNotes Dietary risk factors that can lead to the development of GDV include food characteristics and feeding practices or behaviors.

Patient positioned in dorsal recumbency. The camera port is placed on the midline just caudal to the umbilicus. The instrument port is placed just lateral to the right margin of the rectus abdominus and 3 to 5 cm caudal to the last rib. Courtesy of Clarence Rawlings, DVM, PhD, DACVS.

cannula assembly should be large enough to accommodate 10-mm instrumentation. Transilluminate the incision site to identify and avoid abdominal wall vessels. Nerves parallel vessels; thus, avoiding the vessels reduces the risk of hemorrhage and nerve injury. Pass a 10-mm laparoscopic Babcock or DuVall (FIGURE 2) forceps through the instrument port to manipulate the cranial abdominal organs and obtain an unobstructed view of the antrum of the stomach. Then grasp the FIGURE 2

10-mm DuVall laparoscopic forceps are useful for grasping the antrum of the stomach.

Courtesy of Clarence Rawlings.

mixed-breed dogs are also predisposed. Various non–breed-associated risk factors have been shown to be associated with GDV. Nondietary risk factors include lean body condition, older age, male sex, increased thoracic depth-to-width ratio, first-degree relative with GDV, aggressive or fearful temperament, histologic evidence of inflammatory bowel disease, and increased hepatogastric ligament length.15 Dietary risk factors that can lead to the development of GDV include food characteristics— small food particle size and the presence of oil or fat among the first four ingredients of a dry food—and feeding practices or behaviors, including feeding a large amount of food, once-daily feeding, feeding from an elevated bowl, eating quickly, and aerophagia.15 Based on these risk factors, it may be reasonable to conclude that certain canine subpopulations are at such a high risk of developing GDV that they could be considered good candidates to receive prophylactic treatment.

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Section Name

FIGURE 3

The antrum of the stomach is grasped using 10-mm Babcock or DuVall forceps.

Courtesy of Clarence Rawlings.

Courtesy of Clarence Rawlings.

FIGURE 4

antrum of the stomach with the forceps midway between the mesenteric and antimesenteric sides, approximately 5 to 7 cm oral to During antral exteriorization, take care to the pylorus (FIGURE 3). This is also the site for avoid twisting. Place stay sutures at either end of the proposed seromuscular incision in the stomincisional gastropexy. ach to aid in exposure. These stay sutures are later Once you have a firm hold on the antrum, removed before closure. evacuate the pneumoperitoneum. Exteriorize the forceps and antrum by removing the right- the mucosa to ensure that the sutures are not side cannula and extending the port incision to placed through the mucosa into the lumen 4 to 5 cm in an orientation parallel to the last and that adequate muscle tissue is exposed rib. During this dissection, use of a muscle- for the gastropexy. Place two simple, continusplitting approach to the external and internal ous lines of 2-0 or 0 synthetic, monofilament, abdominal oblique muscles by incising parallel absorbable suture to appose both margins of to the orientation of their fibers may result in the seromuscular layer in the antrum to the less postoperative pain. The transversus abdo- transversus abdominus muscle (FIGURE 6). Before closure, remove the full-thickness minis is the final layer to be sectioned before the stomach can be exteriorized. During the stay sutures. Close the oblique abdominal musantral exteriorization, take care to avoid twist- cles with interrupted or continuous sutures of ing. As soon as the stomach is visualized, place synthetic, absorbable material, and close the a full-thickness stay suture of 2-0 absorbable remainder of the incision in routine fashion. or nonabsorbable monofilament suture in the After completion, briefly reestablish the pneustomach wall. The forceps can be released at moperitoneum and view the gastropexy laparoscopically to ensure that this point. Place a second stay optimal positioning and orisuture 4 to 5 cm orally or aboSURGICAL entation have been achieved rally. The relative positions of VIDEO and that excessive hemorthese sutures define the extent rhage or body wall defects are of the proposed gastropexy not present (FIGURE 7). (FIGURE 4). To see a video of exteriorizaMake an incision at least 4 After once more evacuattion of the stomach wall, stay suture placement, and initial cm long through the seromusing the pneumoperitoneum, suturing of the seromuscular cular layer of the antrum along remove the midline canlayer of the stomach wall to the long axis of the stomach, nula and close the incision the transversus abdominis avoiding the larger blood ves(FIGURE 8). Closure of any muscle, visit the Web port-site incisions that are 5 sels emerging from the greater Exclusives section of mm or larger should include and lesser curvatures (FIGURE CompendiumVet.com. 5). Dissect this incision from body wall closure to avoid the

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Section Name

An incision is made through the seromuscular layer (SM) of the antrum along the long axis of the stomach, exposing the underlying gastric mucosa (GM).

Courtesy of Clarence Rawlings.

FIGURE 6

Courtesy of Clarence Rawlings.

FIGURE 5

Placement of the two simple continuous suture lines through the seromuscular layer (SM) of the antral region of the stomach to the transversus abdominus (TA) muscle. (GM = gastric mucosa)

a laparoscopic hernia stapler to close the tunnel opening with three to six staples placed possibility of incisional herniation of abdomi- individually while apposing the tissues with nal viscera. a grasping instrument12; alternatively, a modification of this method has been described in Laparoscopic Gastropexy which the imperforate stoma resulting from the Use of Intracorporeal Stapling Devices anastomosis of the two tunnels was closed Place the dog in dorsal recumbency, clip and with an intracorporeal simple interrupted aseptically prepare the abdomen, and estab- suture pattern of 2-0 or 3-0 nonabsorbable lish a pneumoperitoneum. Place three 10- to monofilament suture material.11 There are significant disadvantages to 12-mm cannulae in the caudal aspect of the right side of the abdomen. Hold the ventral an intracorporeally stapled gastropexy. aspect of the gastric antrum with laparoscopic Full-thickness perforation of the gastric grasping forceps and make a 2- by 5-cm sub- wall was seen in 14% of cases in one study.12 mucosal tunnel with laparoscopic Metzenbaum This complication could lead to contaminascissors and laparoscopic Kelly forceps, using tion and abscess formation. This technique both sharp and blunt dissection. Make a simi- can also be associated with prolonged surgical time.12 A fur ther lar-sized tunnel in the adjacent disadvantage relates to the right lateral abdominal wall SURGICAL significant cost of using disbetween the transverse and VIDEO posable stapling devices. internal abdominal oblique muscles caudal to the last rib. Use of Intracorporeal Insert a 35-mm gastrointestiTo see a video of the Suturing nal anastomosis laparoscopic incisions in the transversus In this totally laparoscopic stapler (Endo-GIA, Covidien abdominis and seromuscular tech nique, the gastropexy is Inc, Mansfield, MA) into the layer of the stomach, visit the created using intracorporeal dissected tunnels and staWeb Exclusives section of suturing techniques alone, ple the stomach to the right CompendiumVet.com. which, while requiring relaabdominal wall. You can use

QuickNotes There are significant disadvantages to an intracorporeally stapled gastropexy.

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Section Name

FIGURE 8

The gastropexy site is viewed laparoscopically to confirm correct position without twisting and to rule out excessive hemorrhage and open defects in the body wall.

QuickNotes Intracorporeal suturing is more technically challenging than laparoscopic-assisted gastropexy.

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Courtesy of Clarence Rawlings.

Courtesy of Clarence Rawlings.

FIGURE 7

Postoperative view of the laparoscopic-assisted gastropexy site.

tively little disposable equipment, do require sion in the seromuscular layer of the stomach. some speciďŹ c instruments. Apart from routine These incisions should be 4 to 5 cm long and laparoscopic equipment, two laparoscopic be adjacent to each other in an orientation needle holders (Szabo-Berci 5-mm, 33-cm lap- parallel to the ventral midline (FIGURE 10). Introduce an approximately 30-cm length aroscopic parrot-jaw needle holders, Karl Storz Endoscopy) are needed to complete the sutur- of 2-0 polyglactin 910 suture on a curved or ski-type needle into the peritoneal cavity by ing successfully. Establish a camera port in a subumbilical passing the needle through the body wall adjalocation as previously described, then estab- cent to the gastropexy site. First, suture the lish two 6-mm instrument ports on midline, lateral wall of the incisions in the transversus one 3 to 4 cm caudal to the xiphoid process abdominis muscle and antrum using a simple and the other midway between the two other continuous pattern. While tying knots, evacuports and directly medial to the traditional site ate the pneumoperitoneum to decrease tension and ensure secure knots and tight suture for open gastropexy (FIGURE 9). Pass a length of 2-0 nylon suture on a lines. Once the lateral margins of the incision 38-mm reverse-cutting 3/8 -circle curved nee- have been sutured, introduce a second piece dle percutaneously at the intended site of of suture and suture the medial margins to the gastropexy, 2 to 3 cm caudal to the last complete the gastropexy. Once suturing is rib and 5 to 8 cm lateral to midline. Grasp complete, remove the stay suture. Close the the needle with a laparoscopic needle holder three midline ports in routine fashion after the within the peritoneal cavity and take a deep, pneumoperitoneum has been evacuated. full-thickness bite through the antrum of the This technique is more technically chalstomach. Then pass the suture back through lenging than laparoscopic-assisted gastropexy the abdominal wall adjacent to its previous and requires the use of some specialized point of entry. This stay suture equipment (i.e., the laparois used as a temporary anchor scopic needle holders). It is SURGICAL to appose the stomach to the more time consuming, but it VIDEO body wall during incising and may be associated with less suturing. postoperative discomfort To see a video of suturing Make the first incision in because it avoids the parameand knot tying using laparothe transversus abdominis dian incision used in the lapscopic needle holders, visit muscle using laparoscopic aroscopic-assisted technique the Web Exclusives section Metzenbaum scissors. Then and therefore reduces tissue of CompendiumVet.com. make a partial-thickness incitrauma.13

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Section Name

Courtesy of Philipp Mayhew.

FIGURE 10

Courtesy of Philipp Mayhew, BVM&S, MRCVS, DACVS.

FIGURE 9

A partial-thickness incision made in the seromuscular layer of the stomach and the transversus abdominis.

are associated with less tissue trauma and postoperative pain than open celiotomy. All the techniques require the use of basic Positions of the three ports used for the laparoscopic equipment and some specialintracorporeally sutured laparoscopic gasized training. We would advise veterinartropexy technique. The most caudal port is in ians wishing to perform these techniques a subumbilical location and is initially used as the to seek further specialized training. In the camera port. Once the two instrument ports are created, the camera is moved to the middle port. case of the totally laparoscopic techniques, some experience with intracorporeal suturConclusion ing using simulators or cadavers is recomIt is generally accepted that all the laparo- mended before performing these procedures scopic techniques described in this article on client-owned animals.

References 1. Burrows CG, Ignaszewski A. Canine gastric dilation-volvulus. J Small Anim Pract 1990;31:495-501. 2. Brockman DJ, Washabau RJ, Drobatz KJ. Canine gastric dilatation/volvulus syndrome in a veterinary critical care unit: 295 cases (1986–1992). JAVMA 1995;207:460-464. 3. Glickman LT, Glickman NW, Pérez CM, et al. Analysis of risk factors for gastric dilatation and dilatation-volvulus in dogs. JAVMA 1994;204(9):1465-1471. 4. Glickman LT, Lantz GC, Schellenberg DB, Glickman NW. A prospective study of survival and recurrence following the acute gastric dilatation-volvulus syndrome in 136 dogs. JAAHA 1998;34(3):253-259. 5. Beck JJ, Staatz AJ, Pelsue DH, et al. Risk factors associated with short-term outcome and development of perioperative complications in dogs undergoing surgery because of gastric-dilatation-volvulus: 166 cases (1992-2003). JAVMA 2006;229:19341939. 6. Ellison GW. Gastric dilatation volvulus. Surgical prevention. Vet Clin North Am Small Anim Pract 1993;23(3):513-530. 7. Hosgood G. Gastric dilatation-volvulus in dogs. JAVMA 1994; 204(11):1742-1747. 8. MacCoy DM, Sykes GP, Hoffer RE, et al. A gastropexy technique for permanent fixation of the pyloric antrum. JAAHA 1982;18:763-768. 9. Fallah AM, Lumb WV, Nelson AW, et al. Circumcostal gas-

tropexy in the dog: a preliminary study. Vet Surg 1982;11:9-12. 10. Ward MP, Patronek GJ, Glickman LT. Benefits of prophylactic gastropexy for dogs at risk of gastric dilatation-volvulus. Prev Vet Med 2003;60(4):319-329. 11. Rawlings CA. Laparoscopic-assisted gastropexy. JAAHA 2002;38(1):15-19. 12. Sánchez-Margallo FM, Díaz-Güemes I, Usón-Gargallo J. Intracorporeal suture reinforcement during laparoscopic gastropexy in dogs. Vet Rec 2007;160(23):806-807. 13. Hardie RJ, Flanders JA, Schmidt P, et al. Biomechanical and histological evaluation of a laparoscopic stapled gastropexy technique in dogs. Vet Surg 1996;25(2):127-133. 14. Mayhew PD, Brown DC. Prospective evaluation of two intracorporeally sutured prophylactic laparoscopic gastropexy techniques compared to laparoscopic-assisted gastropexy in dogs. Vet Surg 2009; in press. 15. Dujowich M, Reimer SB. Evaluation of an endoscopically assisted gastropexy technique in dogs. JAVMA 2008;232(7):1025. 16. Rawlings CA, Mahaffey MB. Prospective evaluation of laparoscopic-assisted gastropexy in dogs susceptible to gastric dilatation. JAVMA 2002;221:1576-1581. 17. Raghavan M, Glickman NW, Glickman LT. The effect of ingredients in dry dog foods on the risk of gastric dilatation-volvulus in dogs. JAAHA 2006;42(1):28-36.

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Techniques for Laparoscopic and LaparoscopicAssisted Biopsy of Abdominal Organs ❯❯ Philipp Mayhew, BVM&S, MRCVS, DACVS Columbia River Veterinary Specialists Vancouver, Washington

At a Glance Patient Preparation and Positioning Page 171

Abdominal Access and Port Positioning Page 171

Liver Biopsy Page 171

Kidney Biopsy Page 173

Gastrointestinal Biopsy Page 173

Pancreatic Biopsy Page 175

Clinical Pearls Page 176

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Abstract: Multiorgan pathology is a common finding during the diagnostic work-up of complex medical diseases in small animals. Collection of cytologic or biopsy samples from several abdominal organs can give the clinician crucial information in guiding therapy. Although many modalities are available for sample collection, laparoscopic and laparoscopic-assisted techniques offer a minimally invasive approach for collection of high-quality biopsy samples from multiple organs during one anesthetic episode. This article discusses the laparoscopic approaches and techniques for multiorgan biopsy in cats and dogs.

D

iagnostic evaluation of many different disadvantages versus surgical biopsy techmedical conditions can be assisted by niques.4 Full-thickness intestinal biopsy obtaining biopsy samples from multiple samples cannot be harvested endoscopiabdominal organs. This sample collection has cally, and access to the lower small intestine is not possible with currently available traditionally been performed several ways. “Open” celiotomy has the advantage of endoscopic technology. Some studies allowing thorough inspection of, and easy have shown the limitations of endoscopiaccess to, all abdominal organs. However, it cally collected biopsy samples for diagnosis the most invasive technique, sometimes ing certain conditions (e.g., lymphoma).5,6 necessitating an incision from the xiphoid Flexible endoscopy does, however, have process to the pubis for access to the cranial the advantage of being an outpatient procedure, allowing direct visualization of and caudal abdominal structures. Ultrasound-guided fine-needle aspiration mucosal lesions, and avoiding the reported or needle-core biopsy techniques can be 12% dehiscence rate of full-thickness surgiused for obtaining samples from the liver, cal biopsies.7 Laparoscopic procedures (performed pancreas, kidneys, and mesenteric lymph nodes.1–3 Ultrasound-guided techniques are entirely within the peritoneal cavity) and minimally invasive, but they require a skilled laparoscopic-assisted procedures (which use ultrasonographer, do not allow access to all laparoscopic manipulation to exteriorize organs areas of the peritoneal cavity, and have been for extraperitoneal surgery) can allow a thorshown to produce inferior samples in many ough evaluation of most abdominal organs. cases when compared with open surgical or It is not known whether laparoscopic exploration of the abdominal cavity can be as laparoscopic biopsy techniques.1–3 Flexible gastroscopy and small intestinal thorough as open exploration. However, endoscopy can be used for harvesting gas- almost all abdominal structures are visible tric and small intestinal biopsy samples.4–6 laparoscopically, and the success of laparoThese techniques have advantages and scopic exploration of the peritoneal cavity

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is limited only by the patience of the surgeon. port position depends on which techniques For example, laparoscopic examination of the are to be performed. In most cases, multiple full length of the bowel is possible but time organs can be accessed through a small numconsuming. Another important variable to con- ber of common instrument ports or one small sider is the reliability of preoperative abdomi- “assist” incision (an incision 2 to 4 cm in length nal imaging. In most cases, when preoperative created by enlargement of a previously placed imaging has identified the location of focal instrument port for exteriorization of abdomilesions or when diffuse disease only is sus- nal organs). Before beginning the procedure, pected, the need for laparoscopic visualization the surgeon should decide the minimum comof all organs is debatable. bination of instrument ports that will provide Compared with open celiotomy, a laparo- access to all organs to be biopsied. Usually, scopic approach has been shown to result in less two or three instrument ports are adequate. postoperative pain8 and a faster return to normal activity9 and may result in fewer and less severe Liver Biopsy wound-healing complications. This article pre- Due to its fi xed location and friable nature, sents some of the technical aspects of harvesting the liver is biopsied using totally laparoscopic biopsy samples using laparoscopic or laparo- techniques. When multiple organ biopsy samscopic-assisted techniques. These techniques ples are needed, the liver sample should be allow clinicians to offer their clients a high like- taken first so that if laparoscopic-assisted prolihood that, similar to open surgery, they will cedures are subsequently performed through obtain high-quality diagnostic samples from larger port incisions, it will not be necessary all the necessary organs during one procedure, to reestablish the pneumoperitoneum for liver when such an approach is clinically indicated. biopsy at the end of the procedure. However, In choosing which diagnostic techniques reinsufflation may be recommended if the surto use, clinicians must balance the desire to geon wishes to confirm adequate hemostasis obtain high-quality biopsy samples from all before completing the surgery. It is wise to the organs in which pathology is suspected in consider performing a full coagulation profile the least invasive way possible against own- before laparoscopic liver biopsy. I place a preers’ financial constraints and tolerance for the tied loop ligature (described below) in animals with coagulopathy or when harvesting large risk of potential complications. samples, although the need or benefit of this Patient Preparation and Positioning practice has not been evaluated scientifically. For all of the techniques described below, the In most cases, when a liver biopsy is perpatient is placed in dorsal recumbency and formed in isolation for diffuse hepatopathy, a sinthe abdomen is liberally clipped from 2 inches gle instrument port suffices. The port is placed cranial to the xiphoid process to the pubis. under direct visualization in a paramedian Laterally, the patient is clipped to approximately the midabdomen level as for a tradiTO LEARN MORE tional open celiotomy. It is important that wide clipping and aseptic preparation be performed in the unlikely event that conversion to an Patient preparation and the Hasson and Veress open procedure becomes necessary. Lateral needle techniques are described in more detail recumbency can be used for access to certain in the August 2008 Surgical Views article, individual organs, but when examination or “Canine Laparoscopic and Laparoscopic-Assisted biopsy of multiple organs is desired, I prefer Ovariohysterectomy and dorsal recumbency and the use of a subumbiliOvariectomy,” available cal telescope port. at CompendiumVet.com.

Abdominal Access and Port Positioning A subumbilical telescope port can be placed using either the Hasson or the Veress needle technique.10 For the following procedures, instrument

QuickNotes Before beginning the procedure, the surgeon should decide the minimum combination of instrument ports that will provide access to all organs to be biopsied.

A video demonstrating the Hasson technique is also available at CompendiumVet.com.

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A needle-core biopsy needle has been placed percutaneously and is inserted into the renal cortex before being discharged. The advantage of the laparoscopic approach is the ability to monitor hemorrhage after withdrawal of the instrument.

QuickNotes In all cases, liver biopsy sites should be visualized until the surgeon is convinced that all hemorrhage has ceased before removing the telescope.

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FIGURE 2

Courtesy of Dr. Mayhew

Courtesy of Philipp Mayhew, BVM&S, MRCVS, DACVS

FIGURE 1

Placement of the wound retraction device produces a small, protected, circular access incision into the peritoneal cavity.

position in either the right or left cranial quad- site with a vessel-sealing device has been rant of the abdomen. Care should be taken not shown in some studies to reduce hemorrhage to place the cannula cranial to the last rib, which associated with the procedure.11,12 Several samples can be taken from multiple risks entering the thoracic cavity and could precipitate pneumothorax. A 6-mm trocar–cannula lobes. By passing the telescope caudally or craassembly can be placed to accommodate 5-mm nially around the falciform fat, access to both cup biopsy forceps. A second port can be placed right and left sides of the liver is possible. If the on the contralateral side if the surgeon plans to surgeon judges that excessive hemorrhage is use a hemostatic device (vessel-sealing device occurring after liver biopsy, a piece of gelatin or ligature) to harvest the sample. If a focal liver sponge or oxidized regenerated cellulose can lesion has been diagnosed from preoperative be passed through a port and manipulated into imaging, the instrument port should be placed position at the biopsy site to promote clot foron the side of the focal lesion. If other laparo- mation and hemostasis. In all cases, the biopsy scopic procedures are to be performed in addi- sites should be visualized until the surgeon tion to the liver biopsy, the instrument ports is convinced that all hemorrhage has ceased used for those procedures can usually be used before removing the telescope. If hemorrhage is of concern (e.g., in anito access the liver, thus minimizing the number mals with advanced hepatic failure, focal or of necessary ports. The simplest way to perform a liver biopsy is highly vascular lesions, or known coagulopaby using 5-mm laparoscopic cup biopsy forceps thies), it may be preferable to apply a pretied to harvest pieces of liver from the edge of a lobe. loop ligature or extracorporeally assembled The tissue is grasped and gently twisted until it loop ligature to ligate the tip of the lobe separates from the rest of the lobe. Care should before taking biopsy samples. This ligation decreases the chance of severe be taken during this process hemorrhage; however, a secto avoid tearing liver parenSURGICAL ond port must be placed for chyma by rough handling, VIDEO application of the ligature. A which can lead to excessive modiďŹ ed Roeder laparoscopic hemorrhage. Performed corTo see videos of a laparoscopic slipknot is used. The loop rectly, this technique has liver biopsy using a 5-mm is passed through the instrubeen shown to cause minimal laparoscopic cup forceps, a ment cannula either with the bleeding in healthy dogs and gelatin sponge, and a pretied plastic application device (for to yield good-quality tissue loop ligature, visit commercial pretied loop ligasamples.11,12 Coagulation of CompendiumVet.com. the periphery of the biopsy tures [e.g., Endoloop, Ethicon

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Endosurgery, Cincinnati, OH] ) or with a knot pusher (for self-assembled loop ligatures). It must then be manipulated into position around the tip of a liver lobe. A blunt probe can aid in elevating the liver lobe during loop positioning. When the loop is in position, it is tied by advancing the plastic application device or knot pusher (for self-assembled loops) against the modified Roeder knot until it securely ligates the blood vessels and bile ducts within the parenchyma. The liver tissue distal to the ligature can then be cut with endoscissors and withdrawn through a cannula, or multiple bites can be taken with laparoscopic cup biopsy forceps. If a large focal liver mass is to be biopsied, extreme care should be taken because these lesions are often very vascular. Consideration should be given to taking a needle-core biopsy sample under laparoscopic guidance before collecting larger samples to gauge the level of hemorrhage that will result. Otherwise, a loop ligature should be used to harvest the sample to reduce the risk of profuse hemorrhage. It may be advisable to use a specimen retrieval bag to remove larger samples. Extension of the port site may be needed to recover these samples.

from the kidney and ensure that hemostasis has been achieved before closure. I prefer to use an automatic spring-activated needle-core biopsy needle to decrease the possibility of inadvertent premature needle withdrawal from the parenchyma that can occur from excessive movement with manually activated Tru-Cut needles. Under direct visualization, the biopsy needle is guided into the parenchyma and directed to pass across the renal cortex to maximize the number of glomeruli recovered13 (FIGURE 1). The sample is taken by activating the biopsy needle, which is subsequently withdrawn from the peritoneal cavity to recover the sample. Usually, one to two samples are taken from one or both kidneys, depending on the nature of the pathology suspected. If the needle is placed too deeply into the medulla, fewer glomeruli may be recovered and there is a greater risk of hemorrhage from arcuate vessels.13 The laparoscopic technique using a 14-gauge needle has been shown to give superior-quality biopsy samples compared with ultrasonographic guidance of the same-size needle.2

Gastrointestinal Biopsy Kidney Biopsy

Biopsies of the small intestine are usually If a single kidney is to be biopsied, a needle- performed using a laparoscopic-assisted techcore biopsy technique is usually selected. nique. In humans, in which the small intestiTheoretically, no instrument port is required nal lumen is significantly larger, endoscopic for this technique because the biopsy needle stapling devices can be used to resect small can be passed percutaneously into the perito- antimesenteric sections of small intestine. This neal cavity in a location directly ventral and would likely result in excessive compromise of somewhat caudal to the kidney. However, it the luminal diameter in small animals and so is is helpful to have one instrument port avail- not practical in these patients. Exteriorization able for passage of a blunt probe that can of bowel segments through a small assist incihelp manipulate the kidney into position for sion, followed by standard small intestinal the biopsy and place pressure on the biopsy biopsy sample collection from the antimessite after needle withdrawal to minimize hem- enteric border, is usually the best technique in orrhage from the site. This instrument port dogs and cats. can be placed on the ventral A technique for laparomidline 5 to 10 cm cranial scopic-assisted small intesSURGICAL or caudal to the telescope tinal biopsy that involves VIDEO port. If an instrument port is placement of a paramedian available, a piece of oxidized port lateral to the right rectus To see a video of a kidney regenerated cellulose can be abdominis muscle has been biopsy using a 14-gauge placed over the biopsy site reported.14 A 10-mm Babcock spring-loaded needle-core forceps is used to grasp a if hemorrhage is profuse. A biopsy needle and oxidized section of duodenum, jejusignificant benefit of laparosregenerated cellulose, visit num, or ileum and bring it copy is the ability to visualize CompendiumVet.com. to the port-site incision. The the amount of hemorrhage

QuickNotes A significant benefit of laparoscopy is the ability to visualize the amount of hemorrhage from the kidney and ensure that hemostasis has been achieved before closure.

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Large segments of small intestine can be removed through the laparoscopic-assisted incision. Using a wound retraction device minimizes pressure on the mesenteric root, preventing vascular engorgement of exteriorized bowel and facilitating its return to the peritoneal cavity after completion of the biopsy.

QuickNotes There are limitations to the use of small assist incisions for abdominal organ biopsy.

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Courtesy of Dr. Mayhew

FIGURE 4

Courtesy of Dr. Mayhew

FIGURE 3

The duodenum has been partially exteriorized through the assist incision. A biopsy sample can easily be harvested from the duodenum in addition to a pancreatic sample, if clinically indicated.

trocar–cannula assembly is removed while the device has several advantages. It prevents comBabcock forceps is still grasping the small intes- pression of the mesenteric root and subsequent tinal loop. To exteriorize the loop of intestine, vascular compromise compared with exteriorthe port incision can be enlarged to 2 to 4 cm, ization of the intestine through an unretracted as needed. A sample can then be harvested incision, thereby allowing large sections of in standard fashion. Using this technique, an intestine to be exteriorized for examination at enterostomy feeding tube can also be placed at any one time (FIGURE 3). It also allows other the time of biopsy, if clinically indicated.14 If a structures such as the pancreas and mesfeeding tube is to be placed, the section of the enteric lymph nodes to be elevated enough small intestine that is grasped must be chosen to easily collect biopsy samples (FIGURE 4). carefully because duodenostomy and jejunos- If the assist incision is directed cranially from tomy feeding tubes are usually placed in the the original subumbilical port location, it is midduodenal or proximal jejunal areas to opti- usually possible to obtain a sample from the stomach, although this may be challenging in mize nutritional absorption during feeding. I often use a modification of this technique large or deep-chested dogs. The wound retracto allow easier access to the small intestine and tion device also prevents contamination of the other organs. Once any laparoscopic procedures wound margin and has been shown in some (e.g., liver biopsy) are completed, the telescope human studies to decrease wound infection is removed from its subumbilical location and rates.15 Alternatives to the wound retractor the port incision enlarged to 3 to 4 cm to allow device include the placement of Gelpi retractors or a small Balfour retractor placement of a 2- to 4-cm in the wound to open the incilaparoscopic wound retracSURGICAL sion and decrease comprestor (Alexis Wound Retractor, VIDEO sion of the mesenteric root. Applied Medical Corp, Rancho There are limitations to the Santa Margarita, CA). Once the To see videos demonstrating use of small assist incisions retractor is in place, the circumthe placement of a wound for abdominal organ biopsy. ferential force exercised at the retractor and use of this It is difficult to exteriorize the wound margin holds open a device in exteriorizing a large proximal descending duodesmall circular orifice into the section of intestine, visit num and the ileocecocolic peritoneal cavity (FIGURE 2). CompendiumVet.com. This relatively inexpensive junction. The colon can be

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Once exteriorized, the small intestine can biopsied in standard fashion. The use of a small-gauge stay suture placed at the antimesenteric border, followed by an incision with a number 11 blade, helps in the atraumatic harvesting of small intestinal biopsy samples.

Courtesy of Dr. Mayhew

FIGURE 6

Courtesy of Dr. Mayhew

FIGURE 5

The laparoscopic-assisted technique allows local lavage to be performed in a location away from the opening into the peritoneal cavity, thus minimizing peritoneal contamination.

exteriorized, although full-thickness colonic abdominal incision site, thus preventing any biopsy is strongly discouraged because of the contamination of the peritoneal cavity with high morbidity associated with dehiscence in lavage solution (FIGURE 6). After completion of this area and the excellent diagnostic quality all procedures, all abdominal wall incision sites can be closed routinely. of colonoscopic biopsy samples.4 With either the modified or unmodified technique, once the intestine is exteriorized, Pancreatic Biopsy samples can be taken using a technique simi- A laparoscopic or laparoscopic-assisted lar to that used during open celiotomy. Using a (FIGURE 4) technique can be used for pancrestay suture of 4-0 suture material, a small, full- atic biopsy. A single instrument port can be thickness bite is placed on the antimesenteric used for the laparoscopic technique if a punch side of the intestine. A number 11 blade is used technique is used, although a second port is to incise the intestine around the stay suture, necessary if use of a vessel-sealing device or ensuring that an adequate sample of mucosa as ligature is desired. A second instrument port well as submucosa and muscularis is harvested may also be necessary if significant manipula(FIGURE 5). A skin biopsy punch can also be tion of the surrounding organs is needed to used for small intestinal biopsy sample col- obtain an unobstructed view of the pancreas. lection.16 The incision(s) can be closed using A pancreatic biopsy is usually performed in 3-0 or 4-0 monofilament absorbable suture addition to biopsy of other organs; therefore, material (e.g., polydioxanone) in a simple, access is usually from instrument ports posiinterrupted or simple, continuous suture pat- tioned for these other biopsy procedures. tern. If significant narrowThe tip of the right (duoing of the luminal diameter denal) limb of the pancreas SURGICAL is anticipated after suturing, is usually the simplest to VIDEO the incisions can be closed sample. Clinical judgment in transverse fashion to prewill help the surgeon deterserve the luminal diameter mine whether this area will To see a video of pancreatic as much as possible. After provide a representative sambiopsy using a 5-mm cup closure of the biopsy site is ple. A 5-mm cup biopsy forbiopsy forceps, visit complete, local lavage can ceps can be used to carefully CompendiumVet.com. be performed away from the remove a small piece of pan-

QuickNotes The tip of the right (duodenal) limb of the pancreas is usually the simplest to sample.

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Courtesy of Dr. Stephen J. Mehler, DVM, DACVS

FIGURE 7

Clinical Pearls Using a combination of laparoscopic and laparoscopic-assisted techniques, a “one-procedure” approach to collection of high-quality organ samples can be achieved in a minimally invasive fashion. Laparoscopic-assisted techniques can allow several organs to be biopsied through one small port incision.

A laparoscopic biopsy sample is being taken from the periphery of the right pancreatic limb using a 5-mm cup biopsy instrument.

creas from the periphery of the lobe (FIGURE 7). Care should be taken to avoid performing a biopsy on the body of the pancreas (to avoid damaging pancreatic ducts) or the area where the caudal pancreaticoduodenal vessels enter the tip of the right pancreatic limb. This technique has been shown to be safe in healthy dogs, with no significant clinical abnormalities detected postoperatively, although histologically some inflammation is seen around biopsy sites.17 To reduce hemorrhage, several other techniques can be used. A pretied loop ligature can be placed around a piece of pancreas to be biopsied, or hemostatic clips can be placed in a V-shape around the tissue segment to be excised. A vessel-sealing device can also be used to harvest the sample. A recent study compared use of the Harmonic Scalpel device (Ethicon Endosurgery Inc, Cincinnati, OH) with the placement of hemostatic clips to harvest pancreatic biopsy samples laparoscopically.11 The Harmonic Scalpel led to a reduction in hemorrhage but resulted in significantly greater inflammation.

When multiple organ biopsies are required, thought should be given to the optimal position of instrument ports to allow access to all organs in question while minimizing the total number of ports required. When taking a liver biopsy sample, it is my preference to use a loop ligature around the tip of the liver lobe in all animals that are known to have coagulopathy.

Conclusion Laparoscopic and laparoscopic-assisted techniques can be used in combination to gather samples from multiple abdominal organs when diagnostic work-up of complex multiorgan pathology is performed. Even though conversion to an open approach should always be discussed with the owners, in most cases laparoscopic techniques can offer a one-procedure approach for collection of high-quality biopsy samples from multiple organs that is less invasive than open celiotomy.

References 1. Cole TL, Center SA, Flood SN, et al. Diagnostic comparison of needle and wedge biopsy specimens of the liver in dogs and cats. JAVMA 2002;220:1483-1490. 2. Rawlings CA, Diamond H, Howerth EW, et al. Diagnostic quality of percutaneous kidney biopsy specimens obtained with laparoscopy versus ultrasound guidance in dogs. JAVMA 2003;223:317-321. 3. Wang KY, Panciera DL, Al-Rukibat RK, et al. Accuracy of ultrasound-guided fine-needle aspiration of the liver and cytologic findings in dogs and cats: 97 cases (1990-2000). JAVMA 2004;224:75-78. 4. Mansell J, Willard MD. Biopsy of the gastrointestinal tract. Vet Clin North Am Small Anim Pract 2003;33:1099-1116.

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5. Willard MD, Lovering SL, Cohen ND, et al. Quality of tissue specimens obtained endoscopically from the duodenum of dogs and cats. JAVMA 2001;219:474-479. 6. Evans SE, Bonczynski JJ, Broussard JD, et al. Comparison of endoscopic and full-thickness biopsy specimens for diagnosis of inflammatory bowel disease and alimentary tract lymphoma in cats. JAVMA 2006; 229:1447-1450. 7. Shales CJ, Warren J, Anderson DM, et al. Complications following full-thickness small intestinal biopsy in 66 dogs: a retrospective study. J Small Anim Pract 2005;46:317-321. 8. Devitt CM, Cox RE, Hailey JJ. Duration, complications, stress and pain of open ovariohysterectomy versus a simple method

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of laparoscopic-assisted ovariohysterectomy in dogs. JAVMA 2005;227:921-927. 9. Culp WTN, Mayhew PD, Bown DC. The effect of laparoscopic versus open ovariectomy on post-surgical activity in small dogs. Proc Am Coll Vet Surg Annu Symp 2008. 10. Gower S, Mayhew PD. Canine laparoscopic and laparoscopicassisted ovariohysterectomy and ovariectomy. Compend Contin Educ Pract Vet 2008;30:430-440. 11. Barnes RF, Greenfield CL, Schaeffer DJ, et al. Comparison of biopsy samples obtained using standard endoscopic instruments and the harmonic scalpel during laparoscopic and laparoscopicassisted surgery in normal dogs. Vet Surg 2006;35:243-251. 12. Vasanjee SC, Bubenik LJ, Hosgood G, et al. Evaluation of hemorrhage, sample size, and collateral damage for five hepatic biopsy methods in dogs. Vet Surg 2006;35:86-91. 13. Rawlings CA, Howerth EW. Obtaining quality biopsies of the liver and kidney. JAAHA 2004;40:352-358. 14. Rawlings CA, Howerth EW, Bement S, et al. Laparoscopic-assisted enterosotomy tube placement and full-thickness biopsy of the jejunum with serosal patching in dogs. Am J Vet Res 2002;63:1313-1319. 15. Horiuchi T, Tanishima H, Tamagawa K, et al. Randomized controlled investigation of the anti-infective properties of the Alexis retractor/protector of incision sites. J Trauma 2007;62:212-215. 16. Keats MM, Weeren R, Greenlee P, et al. Investigation of Keyes skin biopsy instrument for intestinal biopsy versus a standard biopsy technique. JAAHA 2004;40:405-410. 17. Harmoinen J, Saari S, Rinkinen M, et al. Evaluation of pancreatic forceps biopsy by laparoscopy in healthy beagles. Vet Ther 2002;3:31-36.

Call for Papers Are you involved in research? Veterinary Therapeutics: Research in Applied Veterinary Medicine® is a quarterly journal dedicated to rapid publication. We invite the submission of clinical and laboratory research manuscripts in small animal, large animal, and comparative medicine, including pathophysiology, diagnosis, treatment, and prognosis. Prospective, retrospective, and corroborative studies are all welcome. Submitted articles are scheduled to be published 90 to 120 days after acceptance. Contact Cheryl Hobbs, 800-426-9119, ext 52408, or email chobbs@vetlearn.com.

It’s not just therapeutics! i !

If a dose is missed and a 30-day interval between dosing is exceeded, administer SENTINEL Flavor Tabs immediately and resume the monthly dosing schedule. Warnings: Not for use in humans. Keep this and all drugs out of the reach of children. Precautions: Do not use SENTINEL Flavor Tabs in puppies less than four weeks of age and less than two pounds of body weight. Prior to administration of SENTINEL Flavor Tabs, dogs should be tested for existing heartworm infections. Mild, transient hypersensitivity reactions manifested as labored respiration, vomiting, salivation, and lethargy have been noted in some treated dogs carrying a high number of circulating microfilariae.

NADA 141-084, Approved by FDA Brief Summary—For full product information see product insert. Caution: Federal (USA) law restricts this drug to use by or on the order of a licensed veterinarian. Description: SENTINEL® (milbemycin oxime/lufenuron) Flavor Tabs® are available in four tablet sizes in color-coded packages for oral administration to dogs and puppies according to their weight. Milbemycin oxime consists of the oxime derivatives of 5-didehydromilbemycins in the ratio of approximately 80% A4 (C32H45NO7, MW 555.71) and 20% A 3 (C31H43NO7, MW 541.68). Milbemycin oxime is classified as a macrocyclic anthelmintic. Lufenuron is a benzoylphenylurea derivative with the following chemical composition: N-[2,5-dichloro-4-(1,1,2,3,3,3, -hexafluoropropoxy)-phenylaminocarbonyl]-2,6- difluorobenzamide (C17H 8CI2F 8N2O3, MW 511.15). Benzoylphenylurea compounds, including lufenuron, are classified as insect development inhibitors (IDIs). Indications and Usage: SENTINEL Flavor Tabs are indicated for use in dogs and puppies, four weeks of age and older, and two pounds body weight or greater. SENTINEL Flavor Tabs are also indicated for the prevention of heartworm disease caused by Dirofilaria immitis, for the prevention and control of flea populations, the control of adult Ancylostoma caninum (hookworm), and the removal and control of adult Toxocara canis and Toxascaris leonina (roundworm) and Trichuris vulpis (whipworm) infection. Lufenuron controls flea populations by preventing the development of flea eggs and does not kill adult fleas. Concurrent use of an adulticide product may be necessary for adequate control of adult fleas. Dosage and Administration: SENTINEL Flavor Tabs are given orally, once a month, at the recommended minimum dosage of 0.23 mg/lb (0.5 mg/kg) milbemycin oxime and 4.55 mg/lb (10mg/kg) lufenuron. Dogs over 100 lbs. are provided the appropriate combination of tablets.

Adverse Reactions: The following adverse reactions have been reported in dogs after giving milbemycin oxime or lufenuron: vomiting, depression/lethargy, pruritus, urticaria, diarrhea, anorexia, skin congestion, ataxia, convulsions, hypersalivation, and weakness. Efficacy: Milbemycin Oxime Milbemycin oxime provided complete protection against heartworm infection in both controlled laboratory and clinical trials. In laboratory studies, a single dose of milbemycin oxime at 0.5 mg/kg was effective in removing roundworm, hookworm, and whipworm. In well-controlled clinical trials, milbemycin oxime was also effective in removing roundworms and whipworms and in controlling hookworms. Efficacy: Lufenuron Lufenuron provided a 99% control of flea egg development for 32 days following a single dose of lufenuron at 10 mg/kg in studies using experimental flea infestations. In well-controlled clinical trials, when treatment with lufenuron tablets was initiated prior to the flea season, mean flea counts were lower in lufenuron-treated dogs versus placebo-treated dogs. After 6 monthly treatments, the mean number of fleas on lufenuron-treated dogs was approximately 4 compared to 230 on placebo-treated dogs. When treatment was initiated during the flea season, lufenuron tablets were effective in controlling flea infestations on dogs that completed the study. The mean flea count per lufenuron-treated dog was approximately 74 prior to treatment but had decreased to 4 after six monthly doses of lufenuron. A topical adulticide was used in the first eight weeks of the study to kill the pre-existing adult fleas.

SENTINEL Flavor Tabs are palatable and most dogs will consume the tablet when offered by the owner. As an alternative to direct dosing, the tablets can be hidden in food. Administer SENTINEL Flavor Tabs to dogs, immediately after or in conjunction with a normal meal. Food is essential for adequate absorption of lufenuron.

For technical assistance or to report suspected adverse events, call 1-800-332-2761.

SENTINEL Flavor Tabs must be administered monthly, preferably on the same date each month. In geographic areas where mosquitoes and fleas are seasonal, the treatment schedule should begin one month prior to the expected onset and should continue until the end of “mosquito and flea season.” In areas with year-round infestations, treatment should continue through the entire year without interruption.

©2008 Novartis Animal Health US, Inc. SENTINEL and Flavor Tabs are registered trademarks of Novartis AG.

Manufactured for: Novartis Animal Health US, Inc. Greensboro, NC 27408, USA

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In collaboration with the American College of Veterinary Surgeons

Laparoscopic and Laparoscopic-Assisted Cryptorchidectomy in Dogs and Cats ❯❯ Philipp Mayhew, BVM&S, MRCVS, DACVS Columbia River Veterinary Specialists Vancouver, Washington

Abstract: There are many applications for laparoscopy in small animal surgery. A relatively simple one is abdominal cryptorchid castration. Laparoscopic examination of the peritoneal cavity can both aid in the diagnosis of abdominal cryptorchidism and allow treatment using either a totally laparoscopic or a laparoscopic-assisted technique. Minimally invasive cryptorchid castration obviates the need for “open” celiotomy and may thereby reduce postoperative discomfort and wound-related complications in these patients.

At a Glance Advantages Page 275

D

Disadvantages Page 275

Preoperative Assessment Page 275

Instrumentation Page 276

Surgical Techniques Page 278

TO LEARN MORE

For a description of conventional surgical approaches to cryptorchid testes, see the June 2008 article “Cryptorchidism,” available at

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uring embryonic development in male dogs and cats, contraction of the gubernaculum causes progressive migration of the testes from a location just caudal to the kidney to their normal position in the scrotum.1 This migration is typically complete by 2 months of age but can take place as late as 6 months of age in some breeds.1 The cause of cryptorchidism has not been completely elucidated but is likely multifactorial.1 Migration of the testis can cease at any time, with the result that one or both testes can remain in the peritoneal cavity, within the inguinal rings, or in the inguinal area cranial to the scrotum. Owners should be advised that there are several important reasons to castrate a cryptorchid pet. First, cryptorchidism is thought to be a sex-linked autosomal recessive trait in dogs. Further breeding could lead to propagation of this undesirable trait. Second, cryptorchid testes are prone to several pathologic states. CE Article #1

Cryptorchidism Stephen J. Birchard, DVM, MS, DACVS Michael Nappier, DVM The Ohio State University

ABSTRACT: Cryptorchidism is a common clinical problem in dogs and cats. Retained testes can

be unilateral or bilateral, are usually small and atrophied, and vary in location.These factors make

diagnosis and surgical removal challenging in some animals. Diagnosis is confirmed using a variety of

modalities, including diagnostic imaging in difficult cases. Surgical removal of the affected and normal

testes is the treatment of choice.The surgical approach and technique used depend on the location of the retained testis.

ryptorchidism is one of the most common congenital defects seen in small animal practice. In dogs, the reported prevalence of cryptorchidism ranges from 0.8% to 10%.1 The defect is a sex-linked autosomal recessive trait that is common in certain breeds,2 such as Chihuahuas, miniature schnauzers, Pomeranians, poodles, Shetland sheepdogs, and Yorkshire terriers. Smaller breeds are 2.7 times more likely to be cryptorchid than larger breeds.3 In cats, one study found Persians to be predisposed to cryptorchidism.4 Due to the thermal suppression of sperm production, bilaterally cryptorchid animals are sterile, while unilaterally cryptorchid animals are usually fertile.5 Undescended testes are 13.6 times more likely to develop neoplasia (Figure 1) than normal testes and are at increased risk of torsion.6,7 Undescended testes vary in their anatomic position. They may be located in the prescrotal area, inguinal region, or abdominal cavity. In a study of 240 cryptorchid dogs and 50 cryptorchid cats, retained testes were most commonly found in the right inguinal region in • Take CE tests dogs and in the left or right • See full-text articles inguinal region in cats.8 LocatCompendiumVet.com ing an ectopic testis can be dif-

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ficult in some animals. A thorough and systematic approach to patient evaluation is necessary to efficiently find and remove the abnormal testis. Although surgery for removal of cryptorchid testes is well described in the veterinary literature, approaches to diagnosis and localization of ectopic testes have not been extensively described. This lack, coupled with the increasing number of animals that present with an unknown neutering history (e.g., rescue animals), emphasizes the need for a discussion of a thorough clinical approach to cryptorchidism. This article describes a systematic approach to the diagnosis and surgical treatment of cryptorchidism in dogs and cats, including the integration of the history; physical examination; blood tests, including hormone assays; and diagnostic imaging to make a definitive anatomic diagnosis. Various options for surgical removal of the retained testis are also described.

DIAGNOSIS History Most authors agree that if one or both testes are not present in the scrotum by 2 months of age, the animal is cryptorchid. 2 It is highly unlikely that the testes will descend into the scrotum after this age. The clinical signs of COMPENDIUM

Testicular tumors develop much more frequently in cryptorchid testes than in scrotal testes. In one study, the risk of tumor development in cryptorchid testes was 13.6 times the risk in scrotal testes.2 Inguinally retained testes appear to be at even higher risk of developing neoplasia than abdominally retained testes.3 The risk of testicular torsion is also increased for cryptorchid testes, with torsed testes often being neoplastic.4 If, on physical examination, one or both testes are not present inguinally or scrotally, the missing testis is most likely within the peritoneal cavity. Palpation should be performed carefully because cryptorchid testes are often smaller than descended testes and can be difficult to find. Traditionally, abdominal testes have been removed through either a ventral midline celiotomy or a parapreputial laparotomy.5 Totally laparoscopic or laparoscopic-assisted techniques now exist, allowing removal of intraabdominal testes through much smaller incisions. Neoplastic cryptorchid testes can also be removed laparoscopically, although if the tumor is very large, open surgery may remain more practical.

Compendium: Continuing Education for Veterinarians® | June 2009 | CompendiumVet.com


Advantages A minimally invasive approach to abdomi-nal cryptorchid testis removal reduces tissue trauma and is likely to reduce postoperative pain and wound healing complications com-pared with open laparotomy. If localization of a cryptorchid testis is challenging, laparo-scopic examination of the caudal peritoneal cavity and the entrance to the inguinal rings provides excellent visualization and can help to rule out the diagnosis of abdominal cryptorchid-ism. This may help to minimize iatrogenic dam-age to surrounding structures, which has been attributed in some cases to inadequate visual-ization when small paramedian laparotomies are performed. Such damage includes inad-vertent prostatectomy and ureteral or urethral trauma.6–8

Disadvantages The principal disadvantage of laparoscopy is the need for specialized equipment and the associ-y ated costs. Adequate training is also necessary to perform laparoscopic procedures and to use the equipment appropriately. Although surgi-cal time can initially be longer than that for an open procedure, with experience, laparoscopic cryptorchidectomy is likely to become as efficient, if not faster than, its open counterpart.

Preoperative Assessment A careful history should be taken for any male cat or dog in which two testes cannot be palpated in the inguinal area to ensure that one or both testes have not been removed previously. Generally, a male dog or cat in which one or both testes are absent from the scrotum at 6 months of age is classified as cryptorchid because scrotal migration of a testis after this time is extremely unlikely.1 It is important to assess the inguinal area carefully with the animal under heavy sedation or general anesthesia so as not to miss the presence of an inguinal testis. If one testis is present scrotally and one abdominally, it is also helpful to identify whether the right or left testis is present

It is with great pleasure that I announce the new partnership of the American College of Veterinary Surgeons (ACVS) with Compendium in the “Surgical Views” series. The expertise and experience of the ACVS Diplomates will add greatly to the value of the series. Elizabeth M. Hardie, DVM, PhD, DACVS North Carolina State University

The ACVS is proud to enter into this new cooperative venture with Compendium and series editor Elizabeth Hardie. The ACVS is well known as a world leader in developing innovative surgical procedures and disease research, yet continuing education is also one of the pillars of the College. In addition to presenting at our yearly symposium, ACVS Diplomates host and produce much of the continuing education in veterinary surgery in the United States. Now, with this collaboration, we are expanding our education outreach to a new venue. The ACVS hopes you will enjoy and profit from our Diplomates’ contributions to this distinct continuing education effort. Larry R. Bramlage, DVM, MS, DACVS Chair, ACVS Board of Regents

To locate a Diplomate, ACVS has an online directory that includes practice setting, species emphasis, and research interests (acvs.org/VeterinaryProfessionals/FindaSurgeon).

QuickNotes Generally, a male dog or cat in which one or both testes are absent from the scrotum at 6 months of age is classified as cryptorchid because scrotal migration of a testis after this time is extremely unlikely.

within the peritoneal cavity. This can be done by gentle manipulation of the scrotal testis in a cranial direction, which will usually reveal the side on which it is located. If no inguinal testes are palpated, it can be assumed that the missing testes are in either the inguinal canal (which is uncommon) or the abdomen. Abdominal ultrasound can be used to confirm the presence SURGICAL of abdominal or inguinal canal testes VIDEO in most cases. If doubt still remains about the presence or absence of testes, a human chorionic gonadotropin To see a video of manipulation to stimulation test can be performed to identify which testis is cryptorchid, confirm the presence of testicular tisvisit CompendiumVet.com. sue.5 For this test, serum samples are

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FIGURE 1

FIGURE 2

In many cases, the cryptorchid testis is readily visible during initial visualization of the peritoneal cavity. In this case, the testis can be seen on the right side, lateral to the descending colon and bladder.

Port position for a totally laparoscopic approach for abdominal cryptorchidectomy in a dog. The subumbilical telescope port is placed first, followed by two paramedian instrument ports.

QuickNotes Laparoscopic examination of the caudal abdomen is a minimally invasive modality for confirming the presence or absence of abdominal testes.

276

Laparoscopic examination of the caudal abdomen is a minimally invasive modality for confirming the presence or absence of abdominal testes, and laparoscopic or laparoscopicassisted techniques have been described for removal of abdominally cryptorchid testes.

collected before and 2 hours after administra- Instrumentation tion of human chorionic gonadotropin (50 IU/ As well as the basic components of an endokg IM) and submitted for testosterone assay. scopic tower,10 other equipment required to Unilateral or bilateral monorchidism is very perform laparoscopic and laparoscopic-assisted rare; therefore, it is most likely that abdomi- cryptorchidectomy includes a laparoscope, two nal testes are present,7,9 making exploration of or three trocar–cannula assemblies, and lapthe peritoneal cavity a reasonable next step. aroscopic surgical instruments. The most comTypically, exploration is accomplished via open monly used laparoscope size is 5 or 10 mm, and surgery through a ventral midline celiotomy or the most common lens angles are 0° and 30°. a paramedian laparotomy.5 In cats, a standard Trocar–cannula assemblies can be disposable or ventral midline laparotomy that must usually reusable and are usually 6 mm in diameter to extend caudally to the pubis is performed. fit 5-mm instrumentation. Typically, sterilizable, reusable cannulas are more cost-effective than single-use devices for veterinary use. TO LEARN MORE Instruments essential for laparoscopic cryptorchidectomy include a blunt probe for tissue manipulation and Kelly or Babcock forceps for grasping the testis, spermatic cord, and Basic laparoscopic equipment and the Hasson gubernaculum. For hemostasis during totally and Veress needle techniques are described in the August 2008 article, “Canine Laparoscopic laparoscopic cryptorchidectomy, either a vesand Laparoscopic-Assisted sel-sealing device (e.g., Ligasure [Valleylab Inc., Ovariohysterectomy and Boulder, CO], Enseal [Ethicon Endosurgery, Ovariectomy,” available at Cincinnati, OH], Harmonic Scalpel [Ethicon CompendiumVet.com. Endosurgery, Cincinnati, OH]) can be used. A video demonstrating If these devices are not available, hemostasis the Hasson technique can be achieved using either hemostatic clips is also available at dispensed by a laparoscopic clip applier or CompendiumVet.com. extracorporeal suturing. A knot pusher is used

Compendium: Continuing Education for Veterinarians® | June 2009 | CompendiumVet.com


FTD-0108-004 lepto_8x10.75

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Whether dogs live in a condo or in the backyard, more of them than ever are at risk for leptospirosis – a deadly, zoonotic disease spread by rats, raccoons, squirrels and other wildlife.1,2,3 Protect your patients with LeptoVax™. Its unique subunit purification process is designed to reduce cellular debris for enhanced safety. And with six convenient combinations to choose from, LeptoVax easily accommodates your canine patients and protocols. Contact your Fort Dodge Animal Health representative. Because, wild as it seems, chances are lepto is in your neighborhood, too.

LeptoVax

©2008 Fort Dodge Animal Health, a division of Wyeth. 1. Michael P. Ward, et al. Prevalence of and risk factors for leptospirosis among dogs in the United States and Canada: 677 cases (1970-1998). JAVMA, Vol. 220, No. 1, January 1, 2002. 2. George E. Moore, et al. Canine Leptospirosis, United States, 2002-2004. Emerging Infectious Diseases, www.cdc.gov/ncidod/eid/vol12no03/05-0809.htm. Vol. 12, No. 3, March 2006. 3. Michael P. Ward, et al. Evaluation of environmental risk factors for leptospirosis in dogs: 36 cases (1997-2002). JAVMA, Vol. 225, No. 1, July 1, 2004.


FIGURE 3

The spermatic cord and vascular pedicle of the testis can be seen entering the inguinal ring in this dog. This finding confirms that the testis is located extraperitoneally.

to place extracorporeal sutures. If a testicular tumor is suspected, resection and placement into a specimen retrieval bag before removal from the peritoneal cavity is advised to avoid port site metastasis.

QuickNotes The possibility of conversion to an open approach should always be anticipated with any laparoscopic procedure.

SURGICAL VIDEO

Surgical Techniques Patient Preparation and Positioning Dogs and cats with cryptorchid testes should be positioned in dorsal recumbency on the surgical table. The inguinal area should be thoroughly palpated again to rule out an inguinally located testis and prevent unnecessary laparotomy or laparoscopy. The entire ventral abdomen from the scrotum to the xiphoid process and laterally to the midabdominal level should be aseptically prepared, as the possibility of conversion to an open approach should always be anticipated with any laparoscopic procedure. After initiating the pneumoperitoneum, place the animal in a 20° to 30° “head down” (Trendelenburg) position to allow caudal peritoneal organs to move cranially, thus improving visualization of the area. In some cases, it may also be beneficial to tilt the animal laterally to better visualize one or both testes.

To see a video of the use of a vessel-sealing device to seal and section the gubernaculum, spermatic cord, and vascular pedicle, visit CompendiumVet.com.

278

FIGURE 4

Only the gubernaculum (no vascular pedicle or spermatic cord) can be seen entering the inguinal ring in this dog. This confirms that the testis is within the abdomen, and a thorough examination of the caudal peritoneal cavity should reveal its location.

Once the telescope port has been established, an instrument port can be established using a 5or 10-mm trocar–cannula assembly under direct visualization in a paramedian location (lateral to the prepuce in dogs; in the left or right caudal quadrant of the abdomen in cats) on the right or left side, depending on which testis is located in the abdomen. Every effort should be made to avoid iatrogenic damage to the caudal superficial epigastric vessels during cannula placement. In most bilaterally cryptorchid animals, the side that the instrument port is placed on is not critical because both testes will still be retrievable from the same port.9 A totally laparoscopic technique is usually performed using a three-port technique. A two-port technique can be used if an operating laparoscope with a working channel is used. A camera port should be placed in a subumbilical position. Two more instrument ports are established in paramedian (lateral to the prepuce) positions on both sides of the prepuce in dogs (FIGURE 1) and in a triangulating position around the caudal abdomen in cats.

Exploration of the Caudal Peritoneal Cavity Port Position Laparoscopic-assisted cryptorchidectomy can be performed using a two-port technique. A telescope port is established in a subumbilical location, using either the Hasson technique or a Veress needle technique. These techniques were described in an earlier Surgical Views article.10

In many cases, after establishment of a pneumoperitoneum, the abdominal testis can be seen immediately on entering the peritoneal cavity with the laparoscope (FIGURE 2). However, if confusion exists, the area of the internal inguinal ring should be visualized. If the spermatic cord and vascular pedicle of the testis are seen entering the ring, the testis is in an extraperito-

Compendium: Continuing Education for Veterinarians® | June 2009 | CompendiumVet.com


neal location, either within the inguinal canal or (more likely) in an inguinal location (FIGURE 3). The surgeon should reevaluate the inguinal area if no testis was palpated in that location previously. If only the gubernaculum is seen entering the inguinal ring, the testis is located within the peritoneal cavity, and further inspection of the caudal abdomen usually locates it. Gentle traction can also be placed on the gubernaculum to help in localization (FIGURE 4). In some cases, the testis is obscured by the bladder or other surrounding structures.

Laparoscopic-Assisted Cryptorchidectomy The laparoscopic-assisted cryptorchidectomy technique provides a rapid, simple way to recover an abdominal testis and ligate the vascular pedicle and spermatic cord outside the abdominal cavity, thereby obviating the need for intracorporeal ligation techniques.9 In this technique, laparoscopic Kelly or Babcock forceps are placed through the instrument port to grasp the testis or the spermatic cord. At this point, it is helpful to evacuate the pneumoperitoneum to decrease tension during elevation of the testis. Enlarge the port incision by separating the parallel fibers of the rectus abdominus just enough to remove the

Clinical Pearls Laparoscopic examination of the caudal peritoneal cavity can be very helpful in localizing cryptorchid testes and can prevent an unnecessary celiotomy. Laparoscopic-assisted abdominal cryptorchidectomy is a simple, rapid technique that does not require specialized equipment beyond the basic laparoscopic instrumentation. In many cases, neoplastic cryptorchid testes can be removed using a laparoscopic technique. If the testis is ≥8 cm in diameter or has significant adhesions to surrounding structures, it may be more practical to perform a ventral midline celiotomy.

testis from the peritoneal cavity. Once the testis has been exteriorized, clamp and double ligate the spermatic cord and vascular pedicle before sectioning. It is important to ensure that ligated pedicles are not bleeding and do not become caught in the subcutaneous fat or muscular tissue of the body wall as they are returned to the peritoneal cavity. If both testes are in the peritoneal cavity, they can usually be recovered through the same port incision. To locate the second testis, reestablish the pneumoperitoneum. If the instrument port was enlarged to recover the first testis, use a larger cannula, hold a moistened sponge around the cannula, or place a temporary purse-string suture around the cannula to prevent leakage of carbon dioxide during reinsertion of the cannula. The second testis can then be withdrawn and ligated in the same manner as the first. If the second testis cannot be advanced to the port site, establish a third port on the opposite side of the prepuce (FIGURE 1) and follow the above steps to withdraw the second testis, although in my experience, this is unlikely to be necessary. The port site incision(s) should then be closed, making sure that the ventral sheath of the rectus abdominus is adequately sutured to prevent herniation of abdominal contents, which can occur through defects as small as 5 mm. After closure of the instrument port incisions and before closure of the telescope port, it is advisable to briefly reestablish the pneumoperitoneum and reinsert the telescope to ensure that good hemostasis has been maintained. Finally, remove the telescope, thoroughly purge the pneumoperitoneum from the peritoneal cavity, and close the telescope portal routinely.

QuickNotes If both testes are in the peritoneal cavity, they can usually be recovered through the same port incision.

Totally Laparoscopic Cryptorchidectomy In the totally laparoscopic cryptorchidectomy technique, the vascular supply and spermatic cord are ligated within the peritoneal cavity before the testis is removed from the abdomen. If the testis is directly visible, it can be grasped with laparoscopic Kelly or Babcock forceps and elevated (FIGURE 5), allowing the vascular pedicle and spermatic cord to be moved away from surrounding structures in readiness for ligation. A vessel-sealing device can be placed into the second instrument port, and the guberCompendiumVet.com | June 2009 | Compendium: Continuing Education for Veterinarians®

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FIGURE 5

The testis is elevated for totally laparoscopic cryptorchidectomy to allow better access to the vascular pedicle and spermatic cord during intracorporeal ligation of these structures.

naculum, spermatic cord, and vascular pedicle sealed and subsequently sectioned. The vascular pedicle can be substantial in large dogs, and care should be taken to ensure adequate hemostasis. The Ligasure and Enseal devices are both indicated to seal vessels up to 7 mm in diameter, and I have used them to seal the pampiniform plexus effectively. However, it QuickNotes is suggested that the vascular pedicle be double The vascular pedicle sealed—once proximally and once distally— before sectioning (FIGURE 6). If a vessel-sealcan be substantial ing device is not available, hemostasis can be in large dogs, and achieved using hemostatic clips delivered via a care should be laparoscopic clip applier. Although 5-mm laptaken to ensure ade- aroscopic clip appliers are available, medium quate hemostasis. or large clips are generally delivered in a 10-mm clip applier. To reduce costs associated with the use of expensive single-use disposable clip appliers, multifire sterilizable clip appliers that can be loaded with cartridges of clips are available (M/L-10, Microline Pentax, Beverly, MA). Another alternative for achieving hemostasis of the pedicle is the placement of extracorporeal ligatures. To place extracorporeal sutures, pass a piece of suture material through one cannula and around the pedicles. Withdraw the suture through the same SURGICAL cannula, tie a modified Roeder knot VIDEO outside the peritoneal cavity, push the knot into place through the cannula, To see a video of testis and tighten it around the pedicle using removal through the a laparoscopic knot pusher.11 Although subumbilical port, visit this is the least expensive technique CompendiumVet.com. (it does not require any expensive

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FIGURE 6

The vascular pedicle after sectioning using the vessel-sealing device. The pedicle has been sealed in two different locations approximately 1 cm apart to ensure good hemostasis.

disposable equipment), it is likely to be the most time-consuming because these sutures are tedious to place; however, a rapid learning curve has been seen in studies that used extracorporeal suturing.12 When laparoscopic cryptorchidectomy is performed, the testis must be withdrawn through one of the ports. One of the parapreputial ports can be used for this purpose, or the telescope can be replaced into one of the instrument ports and the testis withdrawn through the subumbilical port. If the subumbilical port is used, any enlargement of the port incision will be through the linea alba, resulting in less muscular trauma and therefore possibly less postoperative pain than if a paramedian instrument port is enlarged. After laparoscopic cryptorchidectomy, it is not necessary to reestablish the pneumoperitoneum because the pedicles are inspected for hemostasis immediately after they have been sealed or ligated and sectioned. After the testis has been removed, all remaining ports can be closed routinely.

Resection of Neoplastic or Torsed Cryptorchid Testes Cryptorchid testes are predisposed to neoplasia and torsion, both of which are indications for surgical excision.1–4 Whether a laparoscopic approach is feasible in these situations depends on several variables. If the testis is very large (8 to 10 cm), a laparoscopic approach may be less practical because a large incision will be required to retrieve the testis after its pedicles have been ligated. A second potential problem

Compendium: Continuing Education for Veterinarians® | June 2009 | CompendiumVet.com


is the presence of adhesions to other structures, specifically the bladder, ureters, prostate, and lower gastrointestinal tract. If the surgeon has any concern about the involvement of these structures or encounters technical difficulties while dissecting adhesions, conversion to an open approach should be considered. However, laparoscopic resection of a neoplastic testis has been reported in the veterinary

literature.13 In my experience, most neoplastic abdominally cryptorchid testes remain small and mobile enough to be resected laparoscopically in a manner similar to those described above for removal of nonneoplastic testes. If a testis is suspected to be neoplastic, it should be placed in a specimen retrieval bag before being pulled through the instrument port to reduce the possibility of port-site metastasis.

References 1. Romagnoli SE. Canine cryptorchidism. Vet Clin North Am Small Anim Pract 1991;21:533-544. 2. Hayes HM, Pendergrass TW. Canine testicular tumors: epidemiological features of 410 dogs. Int J Cancer 1976;18:482-487. 3. Reif JS, Maguire TG, Kenney RM, et al. A cohort study of canine testicular neoplasia. JAVMA 1979;175:719-723. 4. Pearson H, Kelly DF. Testicular torsion in the dog: a review of 13 cases. Vet Rec 1975;97:200-204. 5. Birchard SJ, Nappier M. Cryptorchidism. Compend Contin Educ Pract Vet 2008;30:325-336. 6. Bellah JR, Spencer CP, Salmeri KR. Hemiprostatic urethral avulsion during cryptorchid orchiectomy in a dog. JAAHA 1989;25:553556. 7. Millis DL, Hauptman JG, Johnson CA. Cryptorchidism and monorchidism in cats: 25 cases (1980-1989). JAVMA 1992;200: 1128-1130. 8. Schultz KS, Waldron DR, Smith MM. Inadvertant prostatecto-

my as a complication of cryptorchidectomy in four dogs. JAAHA 1996;32:211-214. 9. Miller NA, Van Lue SJ, Rawlings CA. Use of laparoscopic-assisted cryptorchidectomy in dogs and cats. JAVMA 2004;224:875878. 10. Gower S, Mayhew PD. Canine laparoscopic and laparoscopicassisted ovariohysterectomy and ovariectomy. Compend Contin Educ Pract Vet 2008;30:430-440. 11. Stoloff DR. Laparoscopic suturing and knot tying techniques. In: Freeman LJ, ed. Veterinary Endosurgery. St. Louis: Mosby; 1999:85. 12. Mayhew PD, Brown DC. Comparison of three techniques for ovarian pedicle hemostasis during laparoscopic-assisted ovariohysterectomy. Vet Surg 2007;36:541-547. 13. Pena FJ, Anel L, Dominguez JC, et al. Laparoscopic surgery in a clinical case of seminoma in a cryptorchid dog. Vet Rec 1998;142:671-672.

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In collaboration with the American College of Veterinary Surgeons

Endoscopic Removal of Urinary Calculi ❯❯ Clarence A. Rawlings, DVM, PhD, DACVSa The University of Georgia

At a Glance Patient and Technique Selection Page 476

Preoperative Patient Management Page 477

Transurethral Cystoscopy Page 478

Laparoscopic-Assisted Cystoscopy Page 479

Intraoperative Nephroscopy and Cystoscopy Page 482

Other Minimally Invasive Techniques Page 484

Postoperative Patient Management Page 484

aDr. Rawlings discloses that he

has received financial support from Biovision, Covidien, Ellman International, Endoscopic Support Services, and Karl Storz Veterinary Endoscopy.

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D

espite advances in the prevention 7-kg female dog can usually accommodate and management of urinary cal- a 2.7-mm cystoscope with a 14.5-Fr sheath. culi, calculus removal remains a These dimensions should allow a calcucommon need in small animal practice. In lus 6 to 7 mm in diameter to be removed fact, changes in calculus management have through the urethra. In male dogs, tranincreased the percentage of calculi that are surethral removal is limited to much smaller difficult to manage medically.1 Endoscopic calculi because the stones must traverse the techniques that reduce the need for calcu- os penis region of the urethra. Calculi in lus removal by traditional laparotomy and male cats can be removed by laparoscopiccystotomy have been developed. In my assisted cystoscopy, but the urethra is too experience, most cystic and urethral cal- small for current transurethral cystoscopy culi can be removed by transurethral or techniques. The ability to endoscopically laparoscopic-assisted cystoscopy. These remove cystic and urethral calculi has techniques decrease trauma to and urine largely replaced the need for hydropulsion contamination of the abdomen. Endoscopy in female dogs. also improves the ability to examine the Transurethral cystoscopic calculus removal urinary system for disease and the pres- in female dogs has been enhanced in some ence of more calculi. specialty hospitals by cystoscopic lithotripsy.3–11 As with basket removal of calculi Patient and Technique Selection from the lower urinary tract, lithotripsy can Nearly all calculi in female dogs and cats be more widely used in female dogs than can be removed by either transurethral male dogs. Cystic lithotripsy is indicated cystoscopy or laparoscopic-assisted cystos- for calculi that are too large to be removed copy, in my experience. Most male dogs cystoscopically with baskets. The current can be treated with laparoscopic-assisted contraindications to lithotripsy are large cystoscopy.2 Transurethral cystoscopy is calculi and high numbers of calculi in relapreferred for female cats and dogs because tion to the operator’s expertise. Trauma and it is less invasive than laparoscopic-assisted time required to fragment and remove large techniques; however, calculi must be small or multiple calculi can be excessive during enough to be pulled through the urethra if inappropriate lithotripsy. transurethral cystoscopy is to be successful. Laparoscopic-assisted cystoscopy through Size criteria are continually being modi- one or two small abdominal incisions has fied, but I have found that in female cats proven to be an effective and relatively simple and dogs, calculi can be removed that are way to remove calculi from female and male twice the diameter of the largest cystoscope dogs and cats.2–12 The primary contraindicaappropriate for the patient. For example, a tion is the presence of stones several centi-

Compendium: Continuing Education for Veterinarians® | October 2009 | CompendiumVet.com


meters in diameter that require removal through y a long abdominal incision. Although cystoscopy can still be used to examine the urinary sys-tem after removal of larger calculi, the longer incision might as well be for a traditional lapa-y rotomy and cystotomy. The presence of a very large number of smaller calculi can discourage some endoscopists, but the use of lavage and suction permits removal of larger numbers off stones during laparoscopic-assisted cystoscopy. In the hospitals in which I practice, tradi-tional laparotomy and cystotomy are usuallyy reserved for patients with very large calculi or those requiring other complex abdominal pro-cedures, such as nephrectomy. However, some additional procedures are better performed during laparoscopy than by laparotomy. An example would be a liver biopsy, for which lap-aroscopy is minimally invasive and can be used to obtain multiple tissue samples from selected sites as well as a bile sample for culture. Some subspecialists successfully remove calculi from the ureters and bladder using advanced endourologic techniques.2–11 These techniques are widely performed in people; in the veterinary setting, they have been most commonly applied in larger female dogs. Lithotripsy and endoscopic removal of calculi from the kidneys and ureters are typically referral procedures, in contrast to the endoscopic techniques for transurethral and laparoscopic-assisted cystoscopic procedures, which have been performed by general practitioners trained in endoscopy.

Surgical Views is a collaborative series between the American College of Veterinary Surgeons (ACVS) and Compendium. Upcoming topics in this series include vacuumassisted wound closure, conventional foreign object removal, and suspensory ligament rupture. All Surgical Views articles are peer-reviewed by ACVS diplomates. To locate a diplomate, ACVS has an online directory that includes practice setting, species emphasis, and research interests (acvs.org/VeterinaryProfessionals/FindaSurgeon).

ing techniques are commonly used, but urinary contrast procedures seem to be less frequently employed. Ultrasonography by an experienced ultrasonographer is particularly useful for monitoring dogs with recurrent calculi, especially when the calculi are small. If present, prerenal and postrenal azotemia or uremia should be addressed before calculus removal in all but the most urgent cases of obstruction. Confirmed renal dysfunction may require modification of the plan for calculus removal. In patients with a preexisting urinary FIGURE 1

Courtesy of Chris Herron

Preoperative Patient Management Patient evaluation is directed toward determining renal function, the presence of urinary tract infection, systemic organ function, and the number, size, and distribution of calculi. Tests include a complete blood count, serum chemistry profile, urinalysis, and urine culture. Abdominal radiography is indicated to determine the size, number, and distribution of radiopaque calculi. Radiopaque calculi are composed of struvite, silica, and calcium oxalate; more radiolucent calculi contain urate, uric acid, and cystine. Abdominal ultrasonography is preferred to radiography for detecting radiolucent calculi and helps obtain more information about renal structure and function. Both imag-

Calculus removal from the urethra, bladder, proximal ureter, and renal pelvis frequently involves a 2.7- or 1.9-mm cystoscope with a basket retrieval instrument. The basket retrieval instrument is passed through the cystoscope’s operating channel, and the basket is kept inside the channel until a stone is visualized through the scope. To capture the stone, the basket is advanced through the end of the channel. Once around the calculus, the basket is tightened.

CompendiumVet.com | October 2009 | Compendium: Continuing Education for Veterinarians®

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FIGURE 2

Radiograph showing a urethral calculus (circle). Urine culture results at the time of radiography had no bacterial growth. Using radiography and ultrasonography, the dimensions of the calculi were measured to determine whether transurethral cystoscopy could be used to remove them. The dog weighed 10 kg, and the largest calculus appeared to be 5 mm in diameter.

TO LEARN MORE

tract infection, culture and antibiotic administration should be attempted before emergency relief of urinary obstruction. In patients with recurrent urinary tract infections, collection of a bladder mucosal sample for culture should be considered during calculus removal. Regardless of the protocol used to control urine contamination of the abdomen, the risk of contamination dictates the use of antibiotics during cystoscopy and laparoscopicassisted cystoscopy.

For descriptions of other laparoscopic techniques, see “Laparoscopic-Assisted and Laparoscopic Prophylactic Gastropexy: Indications and Techniques” (February 2009) and “Techniques for Laparoscopic and Laparoscopic-Assisted Biopsy of Abdominal Organs” (April 2009), available on CompendiumVet.com.

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Endoscopic view of the larger calculus at the outflow tract, just before being snared with the basket retrieval device.

Transurethral Cystoscopy Calculus removal using a stone basket is less invasive than and preferred to cystotomy during laparotomy or laparoscopic-assisted cystoscopy if the calculi are small enough for removal via the urethra. The clinician must be a competent and experienced cystoscopist to attempt calculus removal using a basket retrieval instrument. In general, basket removal can be attempted for calculi <3 mm in diameter in female cats and male dogs. In female dogs, calculi removed

The removed calculi were 6 mm in diameter. Despite attempts to medically prevent recurrence, clinical signs developed, and more calculi were diagnosed using ultrasonography and removed by cystoscopy.

Courtesy of Clarence A. Rawlings, DVM, PhD, DACVS

Transurethral cystoscopy in a 6-year-old spayed schnauzer. The patient had a 3-week history of repeated straining to void and inappropriate voiding inside the house. The dog had previously had a cystotomy to remove calcium oxalate calculi.

using this method should be no more than twice the diameter of the largest cystoscope that can be placed in the urethra. Commonly used cystoscope sizes are 1.9 mm for female cats and dogs weighing <5 kg, 2.7 mm for female dogs between 5 and 15 kg, and 3.5 or 4.0 mm for larger female dogs (FIGURE 1). The two smaller cystoscope sizes can be used to retrieve calculi in nearly all female dogs. A 1.9-mm cystoscope and a basket retrieval instrument have been used to remove calculi during cystoscopic examination of the urethra and bladder of male cats after perineal urethrostomy. It is not uncommon during transurethral cystoscopic calculus removal to find lesions that may be related to recurrent urinary tract infections. These include strictures, transitional cell carcinoma, inflammatory polyps, and persisting cystotomy closure sutures. Basket retrieval devices with three or four wires are preferred (FIGURE 1). They should easily fit through the operating channel of the cystoscope. After diagnostic cystoscopy is used to examine the lower urinary tract and flush the bladder, the basket is passed through the

Compendium: Continuing Education for Veterinarians® | October 2009 | CompendiumVet.com


Laparoscopic-Assisted Cystoscopy Cystoscopy via minilaparotomy was initially reported as laparoscopic-assisted cystoscopy.2 Laparoscopic assistance requires a laparoscope and two trocars, in contrast to the more recently reported technique of percutaneous cystolithotomy, also called keyhole transvesicular cystourethroscopy.12 Both laparoscopic-assisted and

FIGURE 3

Courtesy of Chris Herron

operating channel (FIGURE 2). Individual techniques vary, but I prefer to have the bladder only mildly distended and to keep the lavage flow rate low. This practice concentrates the calculi and reduces the swirling effect that can be produced by higher flow rates. Having the patient in dorsal recumbency and tilted with the head up can also move the calculi toward the outflow tract. External abdominal manipulation of the bladder can be helpful. The basket is opened in the area of the calculi and gradually closed during cystoscopic examination. Some clinicians prefer to tighten the wires very securely around the stones. I often use less force to cradle the calculi during extraction. The basket distention helps to gradually dilate the urethra during extraction and reduces the likelihood of calculus fragmentation due to basket compression. This procedure is repeated until all the calculi are removed. Vigorous flushing may be used to remove the smallest calculi. Leaving the cystoscope sheath in the urethra with the cranial end in the outflow tract while squeezing on the bladder can provide a conduit for small calculi to be flushed from the bladder. Laser lithotripsy uses a holmium:YAG laser as well as a cystoscope. Some urologists routinely perform laser lithotripsy of calculi in the bladder, ureters, and kidneys. Patient selection is critical because the time for fracture and extraction can be excessive for large or multiple calculi. Candidates for laser lithotripsy are patients that do not meet the criteria for other forms of endoscopic calculi removal. In general, laser lithotripsy appears to require a longer time for removal of calculi while resulting in a similar percentage of retained calculi as traditional cystotomy.10,11 Clinical studies of minilaparotomy cystotomy have fewer patients, but this technique appears to ensure a very favorable percentage of calculi removal.2,12

The basic scopes used to diagnose and remove calculi are the 2.7-mm rigid cystoscope (top) and the 2.5/2.8-mm flexible fiberoptic urethroscope (bottom). Cats and dogs weighing <5 kg frequently require a 1.9-mm cystoscope. The flexible scope is usually reserved for use in male dogs.

transvesicular cystoscopy require the use of a rigid cystoscope to examine the bladder and urethra and to remove calculi. A 2.7-mm cystoscope is generally used, except in cats and small dogs, for which a 1.9-mm cystoscope is preferred. After calculi are removed from the bladder and outflow tract, the urethra is examined with a rigid cystoscope (female dogs) or a 2.5/2.8-mm flexible fiberoptic urethroscope (male dogs; FIGURE 3). Urethral calculi in male dogs are removed by either retrograde flushing or a basket retrieval device passed beside the urethroscope during laparoscopic-assisted cystoscopy. Urethrostomy is rarely required to remove calculi obstructing the urethra just caudal to the os penis. Laparoscopic-assisted cystoscopy has been combined with other laparoscopic procedures such as liver biopsy or laparoscopic-assisted gastrointestinal foreign body removal. In laparoscopic-assisted cystoscopy, the laparoscope trocar is placed on the midline just caudal to the umbilicus to enable identification of the apex of the moderately distended urinary bladder. A second trocar, through which a 5-mm Babcock forceps can be passed to grasp the apex of the bladder, is then placed (FIGURE 4). The second trocar site is on the midline for female dogs, cats, and some male dogs, depending on the position of the prepuce in relationship to the

QuickNotes Endoscopy improves the ability to examine the urinary system for disease and the presence of more calculi.

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FIGURE 4 Laparoscopic-assisted cystotomy technique.

QuickNotes Setup for laparoscopic-assisted cystotomy. The monitor is to the rear of the patient. A right-handed surgeon stands to the patient’s left (top of illustration). The urinary bladder is mildly distended.

The bladder is secured to the patient, and a minicystotomy is made. A rigid cystoscope and retrieval devices are passed through the minicystotomy.

Calculi can be quickly grasped by placing a retrieval forceps alongside the cystoscope. Basket retrieval devices can also be used.

The cranial margin of the bladder is grasped and lifted to an extended trocar incision site. Insufflation pressure is decreased when the bladder is lifted.

All illustrations © The University of Georgia; photograph courtesy of Chris Herron

Calculi can be removed with a variety of instruments, depending on the size and number of stones.

apex of the bladder. In most male dogs, the sec- just sufficient to secure it to the abdominal wall. ond trocar site is placed laterally (e.g., on the A variety of techniques can be used to keep the left side for a right-handed surgeon). The apex bladder firmly secured to the abdominal wall of the bladder is grasped with the forceps and and prevent urine contamination of the perilifted to the trocar site, which is extended as toneal cavity. In the most common technique, a minilaparotomy (FIGURE 4). If any bladder four quadrate attachments with interrupted lumen is cranial to the trocar site, inspection cruciate sutures are placed, and their long tags and removal of calculi from the cranial pouch are secured to drapes. Some surgeons prefer to of the bladder becomes difficult. The bladder is place a temporary continuous suture between not exteriorized, with the minilaparotomy being the bladder and skin.

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Compendium: Continuing Education for Veterinarians® | October 2009 | CompendiumVet.com


FIGURE 5 Equipment for intraoperative nephroscopy to remove renal calculi.

Intraoperative nephroscopy using a basket retrieval device can be an effective alternative, especially for calculi lodged in the proximal area of the ureter.

Once the bladder is securely sealed to the abdominal wall, a small cystotomy is performed and a rigid cystoscope (1.9 mm for cats and small dogs and 2.7 mm for larger dogs; FIGURE 4) is placed into the bladder. The bladder is lavaged in a fashion similar to that for transurethral cystoscopy. Some clinicians prefer to have a urethral catheter as an additional infusion source. The bladder and entire urethra of female dogs and the prostatic urethra of males are examined with the rigid cystoscope. Calculi can be removed with a variety of instruments, depending on the size and number of stones. Alligator forceps, 5-mm Babcock forceps, and arthroscopic grasping forceps are passed parallel to the cystoscope to grasp and retrieve calculi (FIGURE 4). Another removal technique is to use a wire basket retrieval instrument passed through the operating channel of the cystoscope. The entire assembly of cystoscope and forceps or basket retrieval device is removed with each stone and replaced into the bladder to retrieve the next. Once the larger calculi are removed, some

Illustrations © The University of Georgia

Intraoperative nephroscopy to remove renal calculi is similar to arthroscopy. A grasping device, such as an alligator forceps, is passed beside the cystoscope. Practice with inanimate models can markedly improve calculus retrieval skills.

smaller ones can be flushed from the bladder using urethral catheter flushing and surgical suction. The cystoscope is then advanced through the urethra in female dogs and cats. A 2.5- to 2.8mm flexible urethroscope can be passed from the bladder to the os penis in most male dogs and through the os penis in male dogs larger than 12 to 15 kg. Only the cranial portion of the urethra is examined in male cats. It is common to watch a urethral catheter pass around irregularly shaped calculi without feeling resistance to the catheter’s passage. In my experience, urethral strictures just proximal to the os penis from prior calculi obstruction and trauma are common in dogs. Knowledge of such strictures can justify a scrotal urethrostomy. After calculus removal and flushing, the cystotomy is closed in a single layer, using an appositional suture pattern, avoiding the mucosa. Greater omentum is sutured to the bladder closure. Keyhole transvesicular cystourethroscopy is performed in a similar fashion except that laparoscopy is not used and the apex of the

QuickNotes Practice with inanimate models can markedly improve calculus retrieval skills.

CompendiumVet.com | October 2009 | Compendium: Continuing Education for Veterinarians®

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FIGURE 6

Radiograph showing the renal calculi (arrows). These calculi were diagnosed 6 months before cystotomy to remove them.

QuickNotes Urinary calculi often recur.

One of the calculi is examined during nephroscopy.

bladder is grasped with surgical instruments passed through a small laparotomy.12 Again, it is critical that the cranial portion of the bladder be selected to avoid having bladder cranial to the cystotomy site. The remainder of the procedure is similar. Both laparoscopic-assisted and transvesicular cystoscopy techniques have been reported as being effective in the hands of the technique developers.2,12 Both allow the same excellent examination of the lower urinary tract, limit bladder trauma, limit urine contamination of the abdomen, and should increase the likelihood of complete removal of calculi.

Intraoperative Nephroscopy and Cystoscopy Rigid endoscopy during an open laparotomy causes minimal insult to the urinary system from the renal pelvis to the urethra,13 improves lighting, and increases magnification much more effectively than magnifying loupes and diode head lights. The optical space within the lumen of the renal pelvis and ureters is obtained as for cystoscopy, using saline infusion. The most frequent intraoperative use of endoscopy is to examine the renal pelvis and recesses when removing renoliths.13 The approach is similar to arthroscopy, with a scope being placed through a puncture in the greater curvature (lateral margin) of the kidney. Penetration of the pelvis is easy when the pelvis

482

The removed calculi. Recovery was uncomplicated.

Courtesy of Dr. Rawlings

Removal of renal calculi from a 12-year-old castrated Maltese.

is dilated. Calculi have been removed by using an alligator forceps placed beside a 30° scope or through a separate puncture to achieve triangulation or by using a basket retrieval device placed through the operating channel of the cystoscope (FIGURES 5 AND 6). Unlike nephrotomy, this minimally invasive retrieval of renal calculi using a scope placed through the renal pelvis does not require transient occlusion of renal vessels. The scope can also be passed through the proximal part of the ureter. When removing calculi endoscopically, the renal recesses must be thoroughly examined to ensure complete stone removal. The kidney perforations are closed by firmly apposing their sides or by placing small sutures in the capsule across the perforation. The scope can be used to differentiate between intraluminal calculi and mural calcification. I have also used an arthroscope to examine dilated ureters when removing ureteral calculi or performing a neocystostomy or ureterotomy. Cystoscopes and ureteroscopes have also been used to examine the lumen of the bladder and urethra during traditional laparotomy. Calculus removal via laparotomy in these cases usually involves major procedures such as nephrectomy or removal of stones from the kidney or ureter, which are not amenable to less invasive techniques. The cystoscope can be passed through a minicystotomy before a

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cystotomy is performed, for example, to determine the precise area before resection of an inflammatory polyp.14

Other Minimally Invasive Techniques Calculus removal treatments for dogs and cats are gradually being adapted from those used for people. Laser and electrohydraulic lithotripsy are already being used for cystic calculi in dogs and cats.3–11 Laser lithotripsy and ureteral stenting during ureteroscopy are routinely used for ureteral calculi in people; however, size is a limiting factor in small animals, especially cats and small dogs. In people, renal calculi are removed by percutaneous nephrolithotomy, ureterolithotomy, and cystolithotomy, typically involving lithotripsy, basketing, and flushing. Finally, extracorporeal shock wave lithotripsy is an alternative to reduce calculus size so that urine flow can flush the fragments.13,15

Postoperative Patient Management Case management must be directed to the patient’s needs. At least one lateral radiograph should be taken after calculus removal while the patient is anesthetized to ensure that residual radiopaque

calculi are not present. Appropriate fluid management helps maintain renal function and flush residual blood and calculi fragments. Although laparoscopic procedures are less invasive than traditional surgery, pain medication is routinely used. Typical protocols include administering opioids during the initial recovery period and either NSAIDs or opioids for the first few days after calculus removal. Bupivacaine can be infused into the urethra for additional transient analgesia. Dietary management to reduce calculus formation is usually delayed until the patient is fully recovered and the final calculi analysis obtained. Nutritional therapy soon after surgery should focus on supporting early healing. Urinary calculi often recur. Patients with a history of calculus removal must be closely monitored by the owner and veterinarian. Those with a history of urinary tract infection must have regular urinalysis and, if indicated, urine cultures. When feasible, dietary management should be considered. Dogs and cats in which calculi recur despite good medical management are candidates for ultrasonography studies every 4 to 6 months. Radiography can also be considered for radiopaque calculi.

References 1. Ling GV, Thurmond MC, Choi YK, et al. Changes in proportion of canine urinary calculi composed of calcium oxalate or struvite in specimens analyzed from 1981 through 2001. J Vet Intern Med 2003;17:817-823. 2. Rawlings CA, Barsanti JA, Mahaffey MB, Canalis C. Use of laparoscopic-assisted cystoscopy for removal of calculi in dogs. JAVMA 2003;222:759-761. 3. Senior DF. Electrohydraulic shock-wave lithotripsy for experimental canine struvite bladder stone disease. Vet Surg 1988;22:213-219. 4. Adams LG, Senior DF. Electrohydraulic and extracorporeal shock-wave lithotripsy. Vet Clin North America Small Anim Pract 1999;29:293-302. 5. Lane IF. Lithotripsy: an update on urologic applications in small animals. Vet Clin North Am Small Anim Pract 2004;34(4):1011-1025. 6. Davidson EB, Ritchey JW, Higbee RD, et al. Laser lithotripsy for treatment of canine uroliths. Vet Surg 2004;33:56-61. 7. Grant DC, Were SR, Gevedon ML. Holmium:YAG laser lithotripsy for urolithiasis in dogs. J Vet Intern Med 2008;22(3):534-539. 8. Adams L, Berent A, Moore A, Bagley D. Laser lithotripsy for the removal of uroliths in 73 dogs. JAVMA 2008;232(7):1026-1034.

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9. Defarges A, Dunn M. Use of electrohydraulic lithotripsy in 28 dogs with bladder and urethral calculi. J Vet Intern Med 2008;22(6):1267-1273. 10. Bevan JM, Lulich JP, Albasan H, Osborne CA. Comparison of laser lithotripsy and cystotomy for the management of dogs with urolithiasis. JAVMA 2009;234:1286-1294. 11. Lulich JP, Osborne CA, Albasan H, et al. Efficacy and safety of laser lithotripsy in fragmentation of urocystoliths and urethroliths for removal in dogs. JAVMA 2009;234:1279-1285. 12. Runge JJ, Mayhew P, Berent A, et al. Keyhole transvesicular cystourethroscopy for the retrieval of cystic and urethral calculi in dogs and cats. 43rd Annu Meet Am Coll Vet Surg 2008. 13. McCarthy TC. Otheroscopies. In: McCarthy TC, ed. Veterinary Endoscopy for the Small Animal Practitioner. St Louis: Elsevier Saunders; 2005:423-445. 14. Rawlings CA. Resection of inflammatory polyps in dogs using laparoscopic-assisted cystoscopy. JAAHA 2007;43:1-5. 15. Block G, Adams LG, Widmer WR, et al. Use of extracorporeal shock wave lithotripsy for treatment of nephrolithiasis and ureterolithiasis in five dogs. JAVMA 1996;208(4):531.

Compendium: Continuing Education for Veterinarians® | October 2009

1. Title of Publication: Compendium: Continuing Education For Veterinarians, 2. Publication Number: 1940-8307, 3. Date of Filing: October 1, 2009, 4. Frequency of Issue: Monthly, 5. Number of Issues Published Annually: 12, 6. Annual Subscription Price: $79, 7. Complete Mailing Address of Known Office of Publication: Veterinary Learning Systems, 780 Township Line Road, Yardley, Bucks County, PA 19067, Contact Person: Christine Polcino, Telephone: 267-685-2419, 8. Complete Mailing Address of Headquarters or General Business Office of the Publisher: Veterinary Learning Systems, 780 Township Line Road, Yardley, PA 19067, 9. Full Names and Complete Mailing Addresses of Publisher, Editor, and Managing Editor—Publisher: Derrick Kraemer, Veterinary Learning Systems, 780 Township Line Road, Yardley, PA 19067; Editor: Tracey Giannouris, 780 Township Line Road, Yardley, PA 19067; Managing Editor: Kirk McKay, 780 Township Line Road, Yardley, PA 19067, 10. Owner: Veterinary Learning Systems/MediMedia USA, 780 Township Line Road, Yardley, PA 19067, 11. Known Bondholders, Mortgagees, and Other Security Holders Owning or Holding 1 Percent or More of Total Amount of Bonds, Mortgages or Other Securities: None, 12. Tax Status – Has Not Changed During Preceding 12 Months, 13. Publication Title – Compendium: Continuing Education For Veterinarians, 14. Issue Date for Circulation Data Below: July 2009, 15. Extent and Nature of Circulation—15a.Total Number of Copies (Net Press Run) - Average Number Copies Each Issue During Preceding 12 Months: 53,957, Actual Number Copies of Single Issue Published Nearest to Filing Date: 50,631, 15b(1) Mailed Outside-County Paid Subscriptions Stated on PS Form 3541 - Average Number Copies Each Issue During Preceding 12 Months: 5,631, Actual Number Copies of Single Issue Published Nearest to Filing Date: 4,785, 15b(3). Paid Distribution Outside the Mail Including Sales Through Dealers and Carriers, Street Vendors, Counter Sales, and other Paid Distribution Outside USPS - Average No. Copies Each Issue During Preceding 12 Months: 0, Actual No. Copies of Single Issue Published Nearest to Filing Date: 0, 15c. Total Paid Distribution - Average No. Copies Each Issue During Preceding 12 Months: 5,631, Actual No. Copies of Single Issue Published Nearest to Filing Date: 4,785, 15d(1). Free or Nominal Rate Outside-County Copies Included on PS Form 3541 - Average No. Copies Each Issue During Preceding 12 Months: 45,646, Actual No. Copies of Single Issue Published Nearest to Filing Date: 43,935, 15d(4). Free or Nominal Rate Distribution Outside the Mail - Average No. Copies Each Issue During Preceding 12 Months: 0, Actual No. Copies of Single Issue Published Nearest To Filing Date: 0, 15e. Total Free or Nominal Rate Distribution - Average No. Copies Each Issue During Preceding 12 Months: 45,646, Actual No. Copies of Single Issue Published Nearest to Filing Date: 43,935, 15f. Total Distribution - Average No. Copies Each Issue During Preceding 12 Months: 51,277, Actual No. Copies of Single Issue Published Nearest to Filing Date: 48,720, 15g. Copies not Distributed - Average No. Copies Each Issue During Preceding 12 Months: 2,680, Actual No. Copies of Single Issue Published Nearest to Filing Date: 1,911, 15h. Total - Average No. Copies Each Issue During Preceding 12 Months: 53,957, Actual No. Copies of Single Issue Published Nearest to Filing Date: 50,631, 15i. Percent Paid - Average No. Copies Each Issue During Preceding 12 Months: 11%, Actual No. Copies of Single Issue Published Nearest to Filing Date: 10%, 16. This Statement of Ownership will be printed in the October 2009 issue of this publication. 17. I certify that the statements made by me above are correct and complete: Derrick Kraemer, Publisher.


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Fluid Therapy

445 (US only)

Andis Company

Grooming Tools

449

Banfield, the Pet Hospital

We Believe in Vets

Inside back cover

Bayer Animal Health

Advantage and K9 Advantix

467

Profender

447, 448

resQ

453

Hill’s Pet Nutrition

Prescription Diet r/d Canine

Inside front cover (Canada only)

Northgate Veterinary Supply

Glass cage doors and rod gates

486

PetRays

Free Telemedicine Trial

486

VCA Animal Hospitals

The Latest Technology

461

VCA Antech

Hospital Purchase Program

Inside front cover (US only)

Veterinary Learning Systems

Veterinary Technician

483

Vetstreet

Pet Portals

458, 459

Western Veterinary Conference

2010 Conference

Back cover

WhereTechsConnect.com

Job Marketplace

486

CompendiumVet.com | October 2009 | Compendium: Continuing Education for Veterinarians®

485


3 CE CREDITS

CE Article 2

In collaboration with the American College of Veterinary Surgeons

Vacuum-Assisted Wound Closure: Application and Mechanism of Action ❯❯ Kristin A. Kirkby, DVM, MS, CCRT, DACVS ❯❯ Jason L. Wheeler, DVM, MS, DACVS ❯❯ James P. Farese, DVM, DACVS ❯❯ Gary W. Ellison, DVM, MS, DACVS

❯❯ Nicholas J. Bacon, MA, VetMB, DECVS, MRCVS, DACVS ❯❯ Colin W. Sereda, DVM, MS, DACVS ❯❯ Daniel D. Lewis, DVM, DACVSa University of Florida

Abstract: Vacuum-assisted closure (VAC) is a wound management therapy that creates local negative pressure over a wound bed to promote healing. Benefits of VAC therapy include removal of fluid from the extravascular space, improved circulation, enhanced granulation tissue formation, increased bacterial clearance, and hastening of wound closure. This article describes the mechanism of action of VAC therapy, reviews application techniques, and lists potential complications and contraindications.

At a Glance Equipment and Application Page 568

Beneficial Effects and Mechanism of Action Page 572

Complications and Contraindications Page 576

aDr.

Lewis discloses that he has received financial support from Arthrex Vet Systems and Imex Veterinary.

568

V

acuum-assisted closure (VAC) is a and promoting abscess formation.1,4 VAC noninvasive, active wound manage- therapy is applicable for the treatment of ment system that subjects a wound several wound types (BOX 1). A VAC system consists of several essenbed to subatmospheric pressure within a closed environment. Within this closed, tial elements: sterile open-cell polyurethane negative-pressure environment, VAC ther- foam (pore size: 400 to 600 μm), plastic apy removes fluid from the extravascular egress tubes, occlusive plastic adhesive space, improves circulation, and enhances film, suction tubing, a collection reservoir, the proliferation of granulation tissue.1–4 and an adjustable suction pump capable This article describes the necessary equip- of intermittent or continuous negative ment for, and method of applying, VAC pressures ranging from –50 to –200 mm therapy; reviews the mechanism of action Hg. These components are commercially and benefits; and describes contraindica- available (Kinetic Concepts, Inc. [KCI], San tions and complications. Antonio, TX; Smith and Nephew, London, England). Additional supplies that we have Equipment and Application found useful in applying VAC therapy Basic wound care principles must be fol- include a skin stapler, adhesive paste, and lowed before VAC therapy is initiated. adhesive spray (TABLE 1). Patients are hosProper debridement of devitalized tissue is pitalized for the duration of VAC therapy essential to eliminate any potential nidus (usually 3 to 7 days) and require frequent for bacterial growth and to allow suc- monitoring. An airtight seal is essential to maintain cessful wound closure after VAC therapy.4 Incomplete wound debridement before the continuous negative pressure and prevent application of VAC therapy may result in desiccation of the underlying tissue.1 In the proliferation of granulation tissue over dogs and cats, the hair on the skin adjacent necrotic tissue, delaying wound healing to the wound must be clipped to facilitate

Compendium: Continuing Education for Veterinarians® | December 2009 | Vetlearn.com


JOHN WAS 58 WHEN HE THOUGHT ABOUT RETIREMENT.

THEN HE THOUGHT ABOUT WHO WOULD BUY HIS PRACTICE. VCA Animal Hospitals

PLEASE CONTACT US TODAY.

For more than 20 years, VCA’s hospital purchase programs have given practice owners the freedom to live their lives with peace of mind. More than 475 hospitals in 41 states have joined the VCA family. You have worked hard to create a legacy. VCA’s goal is to continue the success you created. Please contact us if you have a veterinary practice in excess of $1.25 million dollars in annual revenue with 3 or more veterinarians. If you are thinking of selling your practice call VCA. If your hospital is really close to an existing VCA location a merger might be right for you.

Darin Nelson Senior Vice President Development 800-550-2388 (office) 949-228-2525 (mobile) darin.nelson@vcamail.com Neil Tauber Senior Vice President 310-571-6504 (office) 310-890-0444 (mobile) neil.tauber@vcamail.com www.vcaantech.com


FREE

CE Wound Closure Therapy

QuickNotes Basic wound care principles must be followed for all wounds before the application of VAC therapy.

MORE ON THE WEB A companion article on clinical applications of vacuum-assisted wound closure will be published in March 2010.

570

creation of this seal. The foam should be cut to conform to the shape of the wound and placed, fully expanded, directly within the wound so that it is in contact with the entire wound surface, especially the deep margins1,2,4 (FIGURE 1). A plastic, fenestrated egress tube or polyvinyl (red rubber) catheter (10 to 14 Fr) with several additional 2- to 3-mm fenestra-tions is then tunneled into a hole cut into the foam or placed between two pieces of foam.. To avoid pressure necrosis in tissue adjacent to the fenestrations, the egress tube should not be in direct contact with the wound bed.. When the foam and plastic tubing are in place,, the foam can be secured to the wound mar-gins using skin staples (FIGURE 1). To establish an airtight seal, we have found it helpful to apply adhesive spray and a ring of adhesive paste to the skin surrounding the wound before covering the foam and tubing with the adhesive plastic film. The film should extend several centimeters beyond the wound margins (FIGURE 1). The egress suction tube is attached to standard suction tubing and a collection reservoir, which is in turn connected to the vacuum pump with additional suction tubing. We use and recommend continuous suction. The continuous negative-pressure setting most commonly used during VAC therapy is –125 mm Hg.1–6 Initial animal studies showed improved blood flow and granulation tissue formation with intermittent suction (5 minutes on, 2 minutes off)2; however, human patients reported more discomfort when suction was applied intermittently than when it was continuous.1 In our experience, veterinary patients tolerate continuous suction well and do not require pain medication specifically for VAC therapy. When VAC therapy is used postoperatively over a closed incision to prevent seroma and edema formation, a lower negative-pressure setting of –50 mm Hg has been advocated.4 When VAC therapy is used in this manner, the foam can be cut and placed directly over the incision or, if the incision is on a limb, wrapped around the circumference of the limb. If the foam is wrapped circumferentially around a limb, it is essential to cover the entire limb distal to the incision, including the paw, with the foam to prevent a tourniquet effect.

Surgical Views is a collaborative series between the American College of Veterinary Surgeons (ACVS) and Compendium. Upcoming topics in this series include conventional foreign object removal and suspensory ligament rupture. All Surgical Views articles are peer-reviewed by ACVS diplomates. To locate a diplomate, ACVS has an online directory that includes practice setting, species emphasis, and research interests (acvs.org/VeterinaryProfessionals/FindaSurgeon).

When suction is applied, the foam should visibly collapse within the wound and take on a “raisin” appearance beneath the adhesive film (FIGURE 1). The KCI and Smith and Nephew negative-pressure wound care units are equipped with alarm systems to detect air leakage. If one of these pumps is not being used, the appearance and texture of the foam must be checked frequently to ensure that there is no loss of suction. If the airtight seal is lost, measures must be taken to restore the vacuum immediately.

Compendium: Continuing Education for Veterinarians® | December 2009 | Vetlearn.com

Indications for VAC Therapya BOX 1

Large, open, contaminated wounds Skin avulsions Degloving injuries Abdominal and thoracic wounds (e.g., laparotomy surgical sites, open thoracic wounds) Surgical dehiscence Chronic nonhealing wounds Prevention of postoperative seroma and edema Bolster for skin grafts Myofascial compartment syndrome a

Our experience with the use of VAC therapy for these indications will be detailed in a companion article in March 2010.


Your Clients. Their Dogs. Our Thyro-Tabs. ®

(levothyroxine sodium tablets, USP)

Our combination of stability, quality and dependability has produced successful results for nearly three decades. Today, with treatment lines for dogs, horses, and humans, LLOYD, Inc. supplies more levothyroxine sodium to the market than anyone else in the country. Nine dosing strengths. Three package options. One source. Call for a free starter sample.

Caution: Federal law restricts this drug to use by or on the order of a licensed veterinarian. Indications: For use in dogs for correction of conditions associated with low circulating thyroid hormone (hypothyroidism). Dosages: The initial recommended daily dose is 0.1 to 0.2 mg/10 pounds (4.5 kg) body weight in single or divided doses. Dosage is then adjusted by monitoring the T4 blood levels of the dog every four weeks until an adequate maintenance dose is established. Administration: Thyro‑Tabs® may be administered orally or placed in the pet’s food. Warnings: The administration of levothyroxine sodium to dogs to be used for breeding purposes or in pregnant bitches has not been evaluated. There is evidence to suggest that administration to pregnant bitches may in some instances affect the normal development of the thyroid gland in unborn pups. How Supplied: 0.1 mg, 0.2 mg, 0.3 mg, 0.4 mg, 0.5 mg, 0.6 mg, 0.7 mg, 0.8 mg, and 1.0 mg tablets in 28, 120, and 1,000 count. READ PACKAGE INSERT FOR COMPLETE DIRECTIONS


FREE

CE Wound Closure Therapy Components Recommended for Application of VAC Therapy and Approximate Pricea TABLE 1

Component Sterile open-cell polyurethane foam (pore size: 400–600 μm) Plastic egress tube

QuickNotes VAC therapy increases wound circulation, accelerates granulation tissue formation, and removes excess fluid from the extravascular space.

572

Costb $8.00/8" × 12" sheet $8.75

Occlusive plastic adhesive film

$23.25

Skin staples

$23.00

Adhesive spray

$3.75c

Adhesive paste

$22.95

Suction tubing and collection reservoir

$20.00

Suction pump capable of continuous negative pressure

$54.00d

a Essential items are in bold. bPrices listed are based on costs charged to clients at the University of Florida

Veterinary Medical Center. c This cost is not billed to clients because one container can be used for

approximately 20 patients. d This is a daily fee assessed for continuous suction through either central

suction or a VAC machine.

The frequency of VAC bandage changes depends on the characteristics of the wound. VAC bandages are typically changed every 48 to 72 hours,3–5 although initial management of traumatic or highly contaminated wounds may require the bandage to be changed every 24 hours to allow adequate debridement.5,7,8 Culture and sensitivity testing and administration of appropriate antibiotic therapy are indicated for infected wounds. If VAC bandages are left in place for more than 4 to 5 days, granulation tissue may grow into the pores of the open-cell foam, requiring surgical removal of the foam bandage.1 Modifications to traditional VAC therapy have been introduced to treat highly infected wounds or wounds with resistant infections, including silver-impregnated foam (V.A.C. Granufoam Silver Dressing, KCI) and a system that combines negative-pressure wound therapy and antibiotic instillation (V.A.C. Instill, KCI).5 Early results of the use of these systems in highly infected wounds are promising, although no studies of their use been conducted in dogs.8–12 In dogs and cats, bandages can usually be changed with patients under heavy sedation.2 If

VAC therapy is used for long periods of time and multiple bandage changes are performed, the plastic adhesive film can be incised directly over the foam, which can then be removed through the fenestration in the film. Leaving the margins of the original film adhered to the skin reduces skin irritation and minimizes the discomfort experienced during bandage changes by avoiding pulling the film away from the skin. New adhesive film sheets are then placed over the previously applied bandage.7

Beneficial Effects and Mechanism of Action The uniform negative pressure applied to the wound bed by VAC therapy has several beneficial effects, including decreased interstitial edema, increased tissue blood flow, accelerated granulation tissue formation, increased bacterial clearance, and hastened wound closure.1,2 VAC therapy enhances the formation of granulation tissue by increasing capillary blood flow velocity, stimulating endothelial cell proliferation and angiogenesis, narrowing endothelial spaces, and restoring capillary basement membrane integrity.12 Decreased capillary permeability results in reduced edema formation, and the closed, negative-pressure system removes excess interstitial fluid, resulting in decreased local interstitial pressure and restoration of blood flow to previously collapsed vessels.2 An additional mechanism by which VAC therapy increases granulation tissue formation is through mechanical stresses exerted on the wound environment. VAC therapy mechanically stimulates cells by exerting tensile forces on the surrounding tissues.4 The concept that tissues respond to applied forces has long been recognized in relation to bone physiology (Wolff’s law) and is the basis of the Ilizarov technique for distraction osteogenesis.13 In wounds treated with VAC therapy, the cytoskeleton of cells exposed to subatmospheric pressure is altered, resulting in the release of intracellular second messengers and upregulation of cell proliferation.14 VAC therapy is also postulated to increase granulation tissue formation through the removal of substances (e.g., degradative enzymes, proteases, collagenases) that negatively affect wound healing.3 The ability of VAC therapy to enhance bacterial clearance has been debated.2,15–17 Initial animal studies comparing the bacterial clearance of VAC therapy with that of daily saline wet-

Compendium: Continuing Education for Veterinarians® | December 2009 | Vetlearn.com


Be the First to Get Your Feet Wet AAHA Long Beach 2010 registration is open!

AAHA’s Yearly Conference will sparkle in the sands of the Pacific coast in 2010. Register at www.aahanet.org/aahalongbeach2010 or call 800/883-6301 for… advanCEd education – Nearly 300 hours of cutting-edge CE from expert speakers covering the latest medical techniques and the most sophisticated methods of practice management oCEanside enjoyment – One giant playground located right in the heart of Southern California; day or night, the city is always happening exCEptional experience – Outstanding networking opportunities and unmatched personalized service in a less crowded atmosphere We look forward to seeing you at the AAHA Yearly Conference in Long Beach! AAHA LONG BEACH 2010 | MARCH 18-21 | LONG BEACH, CALIFORNIA


FREE

CE Wound Closure Therapy FIGURE 1 Method of VAC bandage application.

A

(A) A large thermal burn on the dorsum of an adult boxer. (B) One week after injury, the eschar has been debrided, leaving a large open wound. Polyurethane open-cell foam is placed within the wound.

B

(C) The margins of the wound are advanced and secured to the foam using skin staples. A polyvinyl catheter has been tunneled into the foam and exits the foam at the upper left wound margin. This catheter is connected to standard suction tubing, which is then connected to a collection reservoir and suction pump. (D) A ring of adhesive paste has been placed around the wound margins, the foam and surrounding skin have been sprayed with adhesive spray, and adhesive film has been placed over the foam and surrounding skin. Negative pressure (–125 mm Hg) has been applied to the bandage, and the foam has contracted beneath the film, taking on a raisinlike appearance and texture.

C

E

D

Approximately 6 weeks after the original injury, the wound is closed and healing appropriately. This wound required approximately 10 days of VAC therapy.

to-dry bandages showed a drop in quantitative bacterial counts in VAC-treated wounds and a peak in bacterial counts in the control group by day 5.2 However, clinical studies evaluating wounds treated with VAC therapy in human patients have failed to show a significant reduction in total bacterial counts.16,17 Irrespective of

574

whether bacterial numbers are reduced, VAC therapy is able to improve a wound’s resistance to bacterial overgrowth through the creation of a healthier wound environment.16 VAC therapy is not, however, a substitute for proper wound management, and wounds must be appropriately debrided before VAC therapy application.

Compendium: Continuing Education for Veterinarians® | December 2009 | Vetlearn.com


Rekindle the warmth of friendship. Atopic dermatitis can disrupt even the best relationships. Restore their closeness by prescribing ATOPICA (Cyclosporine Capsules, USP) MODIFIED. Its targeted action gives dogs lasting comfort without the serious health risks associated with steroids. What could be better than bringing friends back together? As with all drugs, side effects may occur. In a field study, the most common side effects were gastrointestinal signs. Gingival hyperplasia and papillomas may also occur during the initial dosing phase. ATOPICA is a systemic immunosuppressant that may increase the susceptibility to infection. ATOPICA is not for use in reproducing dogs or dogs with a history of neoplasia. ®

The simple joy of comfort © 2009 Novartis Animal Health US, Inc. ® ATOPICA is a registered trademark of Novartis AG.

See Page 576 for Product Information Summary

ATO090302A


Brief Summary: For full product information see product insert. Caution: Federal (USA) law restricts this drug to use by or on the order of a licensed veterinarian. Description: ATOPICA (cyclosporine capsules, USP) MODIFIED is an oral form of cyclosporine that immediately forms a microemulsion in an aqueous environment. Indications and Usage: ATOPICA is indicated for the control of atopic dermatitis in dogs weighing at least 4 lbs body weight. Dosage and Administration: The initial daily dose of ATOPICA is 5 mg/kg/day (3.3-6.7 mg/kg/day) as a single daily dose for 30 days. Following this initial daily treatment period, the dose of ATOPICA may be tapered by decreasing the frequency of dosing to every other day or two times a week, until a minimum frequency is reached which will maintain the desired therapeutic effect. ATOPICA should be given at least one hour before or two hours after a meal. If a dose is missed, the next dose should be administered (without doubling) as soon as possible, but dosing should be no more frequent than once daily. See Product Insert for dosing chart. Contraindications: ATOPICA is contraindicated for use in dogs with a history of neoplasia. WARNINGS: ATOPICA (cyclosporine) is a potent systemic immunosuppressant that may increase the susceptibility to infection and the development of neoplasia. Human Warnings: Not for human use. Keep this and all drugs out of reach of children. For use only in dogs. Precautions: Gastrointestinal problems and gingival hyperplasia may occur at the initial recommended dose. ATOPICA should be used with caution with drugs that affect the P-450 enzyme system. Simultaneous administration of ATOPICA with drugs that suppress the P-450 enzyme system, such as ketoconazole, may lead to increased plasma levels of cyclosporine. The safety and effectiveness of ATOPICA has not been established in dogs less than 6 months of age or less than 4 lbs body weight. ATOPICA is not for use in breeding dogs, pregnant or lactating bitches. Since the effect of cyclosporine use on dogs with compromised renal function has not been studied ATOPICA should be used with caution in dogs with renal insufficiency. There have been reports of convulsions in human adult and pediatric patients receiving cyclosporine, particularly in combination with high dose methylprednisolone. Killed vaccines are recommended for dogs receiving ATOPICA because the impact of cyclosporine on the immune response to modified live vaccines is unknown. As with any immunomodulation regimen, exacerbation of sub-clinical neoplastic conditions may occur. Adverse Reactions: A total of 265 dogs were included in the field study safety analysis. One hundred and eleven (111) dogs were treated with placebo for the first 30 days. For the remainder of the study, all dogs received ATOPICA capsules. Four dogs withdrew from the study after vomiting. One dog each withdrew from the study after diarrhea; vomiting, diarrhea and pruritus; vomiting, depression and lethargy; lethargy, anorexia and hepatitis; gingival hyperplasia, lethargy, polyuria/polydipsia and soft stool; seizure; sebaceous cyst; pruritus; erythema; or otitis externa respectively. Vomiting (30.9%) and diarrhea (20.0%) were the most common adverse reactions occurring during the study.In most cases, signs spontaneously resolved with continued dosing. In other cases, temporary dose modifications (brief interruption in dosing, divided dosing, or administration with a small amount of food) were employed to resolve signs. Persistent otitis externa (6.8%), urinary tract infections (3.8%), anorexia (3.0%), gingival hyperplasia (2.3%), lymphadenopathy (2.3%) and lethargy (2.3%) were the next most frequent adverse events observed. Gingival hyperplasia regressed with dose tapering. Owners of four dogs reported seizures while dogs were receiving ATOPICA. In one dog, seizures were the result of a brain tumor diagnosed one month into the study. Another dog experienced seizures before and after the study. The following clinical signs were reported in less than 2% of dogs treated with ATOPICA in the field study: constipation, flatulence, Clostridial organisms in the feces, nausea, regurgitation, polyuria/ polydipsia, strong urine odor, proteinuria, pruritus, erythema/ flushed appearance, pyoderma, sebaceous adenitis, crusty dermatitis, excessive shedding, coarse coat, alopecia, papillomas, histiocytoma, granulomatous mass or lesion, cutaneous cyst, epulis, benign epithelial tumor, multiple hemangioma, raised nodule on pinna, seizure, shaking/trembling, hind limb twitch, panting, depression, irritability, hyperactivity, quieter, increased light sensitivity, reluctance to go outside, weight loss, hepatitis. Clinical Pathology Changes: During the study, some dogs experienced changes in clinical chemistry parameters while receiving ATOPICA, as follows: elevated creatinine (7.8%), hyperglobulinemia (6.4%), hyperphosphatemia (5.3%), hyperproteinemia (3.4%), hypercholesterolemia (2.6%), hypoalbuminemia (2.3%), hypocalcemia (2.3%) and elevated BUN (2.3%). Post-approval Experience: Neoplasms have been reported in dogs taking ATOPICA, including reports of lymphosarcoma and mast cell tumor. It is unknown if these were preexisting or developed de novo while on ATOPICA. In post-approval drug experience reporting the following additional adverse reactions have been associated with ATOPICA administration in dogs: vomiting, diarrhea, depression/ lethargy, anorexia, pruritus, liver enzyme elevations, trembling, convulsions, polydipsia, polyuria, weight loss, hyperactivity, nervousness, neoplasia. To report suspected adverse reactions or for technical assistance, call 1-800-332-2761. Manufactured for: Novartis Animal Health US, Inc. Greensboro, NC 27408, USA NADA 141-218, Approved by FDA ©2009 Novartis Animal Health US, Inc. ATOPICA is a registered trademark of Novartis AG. NAH/ATO-GC/BS/5 07/08

FREE

CE Wound Closure Therapy Another advantage associated with the use of VAC therapy is the acceleration of wound closure.17 The mechanical forces and improved granulation tissue formation hasten wound contraction, resulting in earlier closure.17 The reduction in time needed to achieve a healthy wound bed, along with the need for fewer bandage changes under sedation, may offer cost savings for VAC therapy compared with conventional dressings that must be changed once or twice daily.17

Complications and Contraindications Complications associated with VAC therapy tend to be minor and easily managed. In our experience, the most common complication is the loss of the airtight seal, which can often be corrected by adding an additional layer of adhesive film. Local dermatitis associated with the bandage is also common but tends to be self-limiting. A significant complication resulted from leaving a VAC therapy dressing in place for 5 days. Granulation tissue grew into the pores in the open-cell foam and necessitated surgical excision of the foam to completely remove the polyurethane fibers. Few complications have been reported in human patients undergoing VAC therapy.5 The most common complication is mild skin irritation from contact with the foam.1,4 Two cases of toxic shock syndrome associated with VAC therapy use have been reported.18 Additionally, chronic complications may result from pieces of foam being left within the wound.5 VAC therapy should be used with caution in hemodynamically unstable patients because

large volumes of fluid can be removed during treatment.3,4 There are several contraindications to VAC therapy. The VAC system has a limited ability to debride wounds, and it will not remove devitalized or necrotic tissue. Thus, VAC therapy should not be used in lieu of proper surgical debridement.1,4 The treatment of osteomyelitis with the VAC system alone is also contraindicated.4,19 The VAC therapy system should not be used in wounds contaminated with malignant neoplastic cells because the application of the VAC therapy bandage will likely increase blood flow and stimulate cellular proliferation within the wound bed.1,4 Finally, care should be taken when placing VAC therapy dressings near exposed arteries and veins. It is possible for the foam to erode through exposed vessels, resulting in extensive blood loss.4,5 Similarly, VAC therapy dressings should be used with caution in patients with coagulopathies or active bleeding.4,5

Conclusion VAC therapy increases local blood flow and enhances granulation tissue formation in wounds, accelerates wound contraction, and removes excessive fluid from wounds. After adequate debridement, VAC therapy can be applied to a wide variety of wounds.

ON THE WEB

The references for this article are available at Vetlearn.com.

CE TEST 2 This article qualifies for 3 contact hours of continuing education credit

3 CE CREDITS

from the Auburn University College of Veterinary Medicine. Subscribers must take individual CE tests online and get real-time scores at Vetlearn.com. Those who wish to apply this credit to fulfill state relicensure requirements should consult their respective state authorities regarding the applicability of this program.

576

Compendium: Continuing Education for Veterinarians® | December 2009 | Vetlearn.com


Index to Advertisers For free information about products advertised in this issue, e-mail the product names to productinfo@CompendiumVet.com. Company

Product

Page #

AAHA

Long Beach 2010 Conference

573

Abbott Animal Health

SevoFlo

544, 545

Antech Diagnostics

FastPanel PCR

551

Banfield, the Pet Hospital

We Believe in Vets

541 (US only)

Bayer HealthCare Animal Health

Advantage Multi for Dogs

552, 553

resQ

539

“A Perfect Fit”

548–549

Boehringer Ingelheim Vetmedica

ProZinc

555, 556

Prescription Diet j/d Canine

Inside front cover (Canada only)

Intervet/Schering-Plough Animal Health

Canine Influenza Vaccine

Back cover

Lloyd, Inc.

Thyro-Tabs

571

Northgate Veterinary Supply

Glass cage doors and rod gates

578

Novartis Animal Health

Atopica

575, 576

P&G Pet Care

NAVC/WVC Symposia

565

Prostora MAX

563 Inside front cover (US only)

Hill’s Pet Nutrition

Sound-Eklin

Veterinary Imaging

VCA Antech

Hospital Purchase Program

569

Vet-Stem, Inc.

Credentialing Courses

Inside back cover

Veterinary Learning Systems

Vetlearn.com

567, 577

Vetstreet

Pet Portals

558, 559

Western Veterinary Conference

2010 Conference

561

WhereTechsConnect.com

Job Marketplace

578

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