FAEP Practitioner Issue 1, 2019

Published by the Florida Association of Equine Practitioners, an Equine-Exclusive Division of the Florida Veterinary Medical Association Issue 1 • 2019

SUBCHONDRAL BONE INJURY IN THE EQUINE FETLOCK KYLA ORTVED DVM, PH.D., DACVS, DACVSMR

SOFT TISSUE INJURIES THAT BLOCK TO A PALMAR DIGITAL (PD) MATTHEW T. BROKKEN DVM, DACVS, DACVSMR

LARYNGOPLASTY AND LARYNGOPLASTY COMPLICATIONS JOHN B. MADISON VMD, DACVS

MENTAL HEALTH AND WELL-BEING IN THE VETERINARY PROFESSION SAMANTHA ROSENTHAL FVMA COMMUNICATIONS

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The President's Line Dear Fellow Equine Practitioners,

EXECUTIVE COUNCIL COREY MILLER

DVM, MS, DACT FAEP COUNCIL PAST PRESIDENT

cmiller@emcocala.com

ANNE L. MORETTA VMD, MS, CVSMT

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JACQUELINE S. SHELLOW DVM, MS REPRESENTATIVE TO FVMA EXECUTIVE BOARD

jackie@shellow.com

ARMON BLAIR DVM

abeqdoc@aol.com

ADAM CAYOT DVM

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AMANDA M. HOUSE DVM, DACVIM

housea@ufl.edu

PHILIP J. HINKLE EXECUTIVE DIRECTOR

phinkle@fvma.org

With 2019 underway and Ocala Equine Conference (OEC) behind us, this year has started off full of great successes and promise for the months to come. As we welcome Dr. Armon Blair into the position of FAEP president in May, we are all very excited about what he will bring to our organization and future programs.

OEC 2019 was held in February in Ocala, Florida with a sold out Comprehensive Equine Ultrasound Wet Lab the Friday before the conference. The topics covered during CE sessions ranged from lameness to internal medicine. Our Exhibit Hall featured companies offering the latest in equine veterinary technology and services, allowing attendees to have one-on-one time for networking. We would also like to thank our OEC sponsors for their support of the program: Sound, KindredBio, Dechra and Stablelab.

Don’t forget to mark your calendars for the 15th Annual Promoting Excellence Symposium (PES) being held October 10-13, 2019 at Sanibel Harbour Marriott Resort & Spa in Fort Myers, Florida. This year’s conference will once again feature a wet lab and a variety of CE sessions to choose from on the most relevant equine veterinary medicine topics. Speakers at this year’s conference will include some of the leading experts in equine veterinary medicine, including Drs. Tom Divers, Alan Nixon and Kurt Selberg. The FAEP Council is putting the finishing touches on this year’s schedule for PES 2019, and registration will be open soon.

FAEP Council member and Representative to the FVMA Executive Board Dr. Jacqueline Shellow was a part of the FVMA delegation who participated in FVMA Legislative Action Days in Tallahassee, Florida in March. Dr. Shellow met with various legislators at the Capitol from her district, along with other notable committee members. Thank you to Dr. Shellow, FVMA members, staff and students who helped raise a powerful voice about legislative issues that will impact the veterinary profession and the well-being of animals.

Another exciting event we look forward to is the 90th FVMA Annual Conference in Tampa, Florida, where Dr. Blair will start his term as the new FAEP president. This will take place during the Awards Ceremony & Installation of Officers event on Friday, May 17, 2019. It is sure to be a very special night and marks the transition of FAEP leadership.

We look forward to all of the great programs and events in the coming year that will allow us to continue the mission of the FAEP. Ruth-Anne Richter, BSc (Hon), DVM, MS FAEP Council President

A Message from Incoming FAEP President Dr. Armon Blair “As the incoming FAEP president, I am acutely aware of the shoes I have to fill. Dr. Richter has done an excellent job leading our organization, and I hope to maintain her high standards for the next two years. It’s always gratifying to plan our continuing education programs and watch them come together successfully. With the experienced and dedicated members of our Council, this task flows smoothly. I am excited to be part of such a great organization and look forward to serving in the years to come.”

Opinions and statements expressed in The Practitioner reflect the views of the contributors and do not represent the official policy of the Florida Association of Equine Practitioners or the Florida Veterinary Medical Association, unless so stated.

Placement of an advertisement does not represent the FAEP’s or FVMA’s endorsement of the product or service.

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2 The Practitioner

Issue 1 • 2019

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EQ U I NE D IVISIO N

SUBCHONDRAL BONE INJURY IN THE EQUINE FETLOCK KYLA ORTVED | DVM, PH.D., DACVS, DACVSMR

INTRODUCTION Subchondral bone injury (SBI) in the metacarpophalangeal joint (MCPJ) and metatarsophalangeal joint (MTPJ) is a common source of pain and lameness in racehorses. Although less common, it is also a cause of lameness in sport horses.1 It is associated with repetitive osseous stress in predictable locations.

SBI can be progressive if it is not detected and treated in a timely fashion, leading to degeneration of the entire joint. The clinical picture associated with these lesions varies between racehorses and sport horses; therefore, these groups of horses will be discussed separately.

RACEHORSES

The MCPJ and MTPJ are at risk of injury in all performance horses, especially those that perform at maximal speeds. In the racehorse, SBI in the fetlock joints has been referred to as palmar osteochondral disease (POD), maladaptive repetitive osseous stress syndrome (MROSS),1 distal cannon bone bruising, and cumulative stress-induced bone injury (CSBI).2 During loading, the joint undergoes hyperextension with proximal dorsal P1 compressing the dorsal aspect of the third metacarpal/metatarsal (MC/MT III) bone, high compressive forces acting on palmar/plantar distal MC/ MT III, and high tension and bending forces acting on the proximal sesamoid bones. SBI is most commonly recognized on the palmar/ plantar distal condyles of the third metacarpal/metatarsal bone, with the medial condyle being more commonly affected in the hindlimbs and the lateral condyle being more commonly affected in the forelimbs (Figure 1).

Bone is able to adapt to training through modeling and remodeling, a process dictated by Wolff ’s law.3 This is especially

Figure 1: Standing, robotic cone-beam CT can be used to diagnose SBI in the equine fetlock early in the disease process, often before radiographic lesions are detectable. The stereotypical crescentic-shaped lesion in the palmar distal aspect of a metacarpal condyle is shown in the transverse, dorsal and sagittal plane images shown here.

Figure 2: Gross pathology images of the metacarpophalangeal (fetlock) joint of Thoroughbred racehorses with mild (left), moderate (middle) and severe (right) SBI affecting the distal palmar condyles. (Images courtesy of Dr. Julie Engiles, University of Pennsylvania.)

true in young racehorses where repetitive cyclic loading causes normal, predictable changes in cortical and cancellous bone.4–6 Bone becomes thicker and denser with increased cyclic loading.

Modeling describes the process by which new bone is formed, whereas remodeling describes the process by which bone is turned over through the activity of osteoclasts (bone resorption) and osteoblasts (new bone formation). This adaptive system can be overwhelmed such that trabecular thickening and sclerosis leads to ischemic injury to osteocytes and subsequent microfracture of the subchondral bone. Failure of the adaptive system can lead to incomplete or complete fractures and/or collapse of the subchondral bone and ulceration of the articular cartilage.

Secondary osteoarthritis is inevitable once the articular surface is involved.

A wide range of morphologic changes is noted depending on severity of the disease. Early in the disease process, gray/blue discoloration of the underlying subchondral bone, with intact articular cartilage, is noted. More severe cases will have collapse of the subchondral bone and complete ulceration of the articular cartilage. Secondary osteoarthritis is often present. Complete failure of the bony column can also be present, as seen with condylar fractures (Figure 2).

Diagnosis

Racehorses will often present with mild-moderate lameness; although, some horses may be acutely, severely lame. Multiple limbs are often involved, in which case a history of poor

4 The Practitioner Issue 1 • 2019

performance may be the only presenting complaint. On lameness evaluation, horses with multiple limbs affected generally have a characteristic short, choppy gait. Joint effusion, heat and positive response to flexion are often absent.

Horses with SBI often do not block out with intra-articular analgesia of the fetlock joint due to the degree of pain originating from the subchondral bone, not the joint. Many horses will have significant improvement in lameness or gait following perineural analgesia of just the metacarpal/metatarsal nerves. These blocks can be performed on the medial or lateral side or both, depending on where the lesion is suspected to be located. Some horses require a complete low four-point block for complete resolution of lameness.

Radiography is almost always performed on horses with suspicion of fetlock lameness; however, it is often not definitive.

In addition to the standard four views, a flexed dorsopalmar/ dorsoplantar view, flexed lateral, and +/- down angle oblique views can be obtained in an attempt to highlight the palmar/ plantar condyles. Nuclear scintigraphy is particularly useful for detecting areas of subchondral bone injury with moderateintense, focal areas of increased radiopharmaceutical uptake (IRU) being the hallmark of this disease.7 Lateral, dorsal-palmar/ plantar, and flexed lateral views should be obtained. Magnetic resonance imaging (MRI) can be very effective for diagnosing early lesions without radiographic changes. MRI examination reveals areas of low-signal intensity in the distal condyles on T1- and T2-weighted sequences, consistent with sclerosis. Focal areas of high-signal intensity are often seen closer to the articular surface on fat-suppressed (STIR) sequences consistent with areas of osteonecrosis.8 Computed tomography (CT) is very effective

for evaluating osseous injury; however, until recently, CT had to be performed under general anesthesia. Recent developments in CT technology have allowed for standing, cone-beam CT to be performed in standing horses. This has provided clinicians with the ability to image the fetlock in 3-D for fast, accurate diagnosis (Figure 3).

Treatment

Horses that are diagnosed with SBI early in the disease process and prior to development of secondary osteoarthritis have a good prognosis for soundness and return to racing, provided they are allowed an adequate period of rest.2 Anti-inflammatories can be useful in the acute/sub-acute period. Treatment with aspirin and/or isoxsuprine does not appear to be effective. Intra-articular injections are rarely beneficial unless OA is present. The use of bisphosphonates is very controversial in SBI. Bisphosphonates induce apoptosis and decrease function in osteoclasts, thereby limiting bone resorption. Although limited resorption may sound appealing on the surface, osteoclastic activity is required to remove necrotic bone present in SBI to allowosteoblasts to lay down healthy, new bone. With this in mind, bisphosphonates are likely contraindicated in these horses. Arthroscopic surgery is generally not indicated due to the inaccessible location of the lesions. Some have advocated surgical drilling or screw placement; however, few long-term studies are available at this time. Recently, Ramzan et al. described screw fixation for unicortical condylar fractures. Although the prognosis for conservative versus surgical treatment was similar, horses treated conservatively had a higher rate of recurrence.9 In our hospital population, we tend to recommend screw placement for linear defects (unicortical fractures) and subchondral cystic lesions.

Figure 3: The robotic cone-beam CT (4DDi) being used to image the front fetlock of a standing horse.

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Prognosis

The prognosis for return to racing is generally good in horses that are diagnosed early in the progression of disease, although racing performance appears to be affected. Tull et al. recently reported successful return to racing in 95 percent of horses with SBI treated with 90 days of small paddock turnout; however, earnings/start decreased significantly following return to racing.2 Additionally, a recent study showed that horses with IRU in the palmar/plantar condyles had significantly fewer starts, reduced earnings and decreased earnings/start compared to age-matched controls.10 Once significant cartilage damage and osteoarthritis has occurred, the disease is progressive and will most likely prevent return to athleticism and may even require fetlock arthrodesis or human euthanasia due to chronic, severe lameness.

SPORT HORSES

The pathophysiology of SBI in sport horses is likely similar to racehorses; however, the repetitive cyclic trauma experienced by the fetlock joint is less intense and SBI may be exacerbated by a single overloading event that causes significant damage to the subchondral bone (i.e. landing poorly off a jump). Unlike racehorses, SBI in the MCPJ or MTPJ is most often seen in mature horses.11 The predilection site for injury is the axial aspect of the proximal phalanx, although the distal aspect of MC/MT III can also be affected. Lesions noted in the axial aspect of the proximal phalanx can include incomplete sagittal fractures. Sport horses tend to display a more insidious onset of lameness, are more likely to have only one limb affected and tend to have more advanced osteoarthritic changes at time of diagnosis. These horses will often present with joint effusion and pain on flexion of the joint.

As with racehorses, radiography appears to be relatively insensitive for evaluating osseous injury unless secondary osteoarthritis is already present. Nuclear scintigraphy can be useful although IRU may be mild and diffuse, compared to racehorses where IRU is usually intense and focal. MRI and CT are particularly helpful in diagnosing SBI in sport horses.

Sport horses are treated in a similar fashion to racehorses; however, there is often more indication to treat the joint, as secondary osteoarthritis is more common. Intra-articular corticosteroids and hyaluronic acid are often used. In our hospital, we often prefer to use regenerative therapies including stem cells, platelet rich plasma and Pro-Stride. Incomplete sagittal fractures and subchondral cystic lesions can be treated with screw placement.

If secondary osteoarthritis is not extensive, sport horses can return to their former level of activity given a prolonged period of rest and rehabilitation.11 Horses with incomplete fractures of the proximal phalanx tend to have a better prognosis compared to horses with more diffuse SBI in the proximal phalanx and distal condyles.

References

1.

Ross MW. Bone bruising – manifestations, diagnosis, imaging and management. In: Proceedings, ACVS Annual Surgical Symposium. 2016:81-94.

2. Tull TM, Bramlage LR. Racing prognosis after cumulative stressinduced injury of the distal portion of the third metacarpal and third metatarsal bones in Thoroughbred racehorses: 55 cases (2000–2009). J Am Vet Med Assoc. 2011;238(10):1316-1322.

3. Chen J-H, Liu C, You L, Simmons CA. Boning up on Wolff ’s Law: Mechanical regulation of the cells that make and maintain bone.

J Biomech. 2010;43(1):108-118.

4. Martig S, Lee PVS, Anderson GA, Whitton RC. Compressive fatigue life of subchondral bone of the metacarpal condyle in thoroughbred racehorses. Bone. 2013;57(2):392-398.

5. Nunamaker DM, Butterweck DM, Provost MT. Fatigue fractures in thoroughbred racehorses: Relationships with age, peak bone strain, and training. J Orthop Res. 1990;8(4):604-611.

6. Holmes JM, Mirams M, Mackie EJ, Whitton RC. Thoroughbred horses in race training have lower levels of subchondral bone remodelling in highly loaded regions of the distal metacarpus compared to horses resting from training. Vet J. 2014;202(3):443-447.

7. Ross MW. Scintigraphic and clinical findings in the Standardbred metatarsophalangeal joint: 114 cases (1993-1995). Equine Vet J. 1998;30(2):131-138.

8. Olive J, Serraud N, Vila T, Germain J-P. Metacarpophalangeal joint injury patterns on magnetic resonance imaging: A comparison in racing Standardbreds and Thoroughbreds. Vet Radiol Ultrasound. 2017;58(5):588-597.

9. Ramzan PHL, Palmer L, Powell SE. Unicortical condylar fracture of the Thoroughbred fetlock: 45 cases (2006-2013). Equine Vet J. 2015;47(6):680-683.

10. Trope GD, Anderson GA, Whitton RC. Patterns of scintigraphic uptake in the fetlock joint of Thoroughbred racehorses and the effect of increased radiopharmaceutical uptake in the distal metacarpal/tarsal condyle on performance. Equine Vet J. 2011;43(5):509-515.

11. Dyson SJ, Murray R. Osseous Trauma in the Fetlock Region of Mature Sports Horses. In: AAEP Proceedings. 2006:443-456.

Dr. Kyla Ortved Dr. Kyla Ortved is an assistant professor of large animal surgery at New Bolton Center, University of Pennsylvania in Kennett Square, PA. She received her DVM degree from the University of Guelph in 2006 and completed her large animal surgical residency training at Cornell University in 2010. Dr. Ortved became boarded with the American College of Veterinary Surgeons in 2011.

Following her residency, she went on to obtain a Ph.D. in equine cartilage repair at Cornell. In February 2016, Dr. Ortved became boarded with the American College of Veterinary Sports Medicine and Rehabilitation. She joined the large animal surgery faculty at New Bolton Center in 2016, where she is focused on orthopedic surgery and research on gene and cell therapies for improving cartilage repair and preventing osteoarthritis.

6 The Practitioner Issue 1 • 2019

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SOFT TISSUE INJURIES THAT BLOCK TO A PALMAR DIGITAL (PD) MATTHEW T. BROKKEN | DVM, DACVS, DACVSMR

Lameness localization is the primary objective when examining a shed some light on possible lameness conditions. Radiographic horse for a performance-limiting condition. While in some horses abnormalities may include cyst-like lucencies or enthesophyte this is possible with an accurate history and clinical examination, formation. Correlating the osseous abnormalities with clinical the vast majority of horses require diagnostic analgesia to significance can be difficult since some can be incidental findings determine the location of lameness. or just a portion of the abnormalities.

Typically, the first perineural block performed in the forelimb is a palmar digital (PD) nerve block. Needle size varies from 22-27 gauge, and variation exists as to how the needle is placed (some veterinarians prefer to angle the needle as far distal as possible).

The author tries to perform the block as low as possible — typically this is just proximal to the collateral cartilages — with a 22-gauge, one-inch needle placed perpendicular to the skin directly over the nerve. Volume of anesthetic should be as little to be effective (typically 1-2 mls per nerve). Typically, this block is evaluated five to 10 minutes after administration. The author also makes sure that the sensitivity to the heel bulbs is lost after the block in every horse to limit the chances of erroneous results.

The PD block has been historically thought to desensitize the palmar one-third of the foot. Recently, studies have shown that the sole, along with pain in the coffin and pastern joints, can be affected by PD analgesia.1-3 Even if using a low volume of anesthetic for the PD block, confusion can occur.4 Numerous reports have documented horses improving with a PD block with injuries more proximal in the limb. King5 reported that 24 of 70 (34 percent) of limbs in horses diagnosed with distal sesamoidean ligament injury improved more than 50 percent with a PD block.5 In another publication, all seven horses with injury to the distal digital annular ligament, where the DDAL was considered the primary source of lameness, improved with a PD nerve block.6 Sampson also noted that three of 24 horses with distal sesamoidean ligament injury improved with a PD block with addition of dorsal branches.7 The author has also identified horses with significant pathology in palmar aspect of the foot that have minimal improvement in lameness following PD analgesia. Typically, these horses improve to a greater extent with the addition of the dorsal branches and/or an abaxial nerve block. The reason for this discrepancy in blocking pattern is unknown.

For lameness localized to the foot, radiographs are typically the first imaging modality chosen. A complete set of foot radiographs should be performed. Since these proceedings are concerned with soft tissue injuries in the foot, the majority of radiographic interpretation/abnormalities will not be covered. However, osseous reaction at the attachments of the soft tissues may be able to

In most cases of foot lameness, ultrasound has limited value due to the hoof capsule and undulations of palmar aspect of the foot.

However, some injuries to the deep digital flexor tendon or the proximal aspect of the collateral ligaments of the coffin joint can be identified with ultrasound. Use of magnetic resonance imaging (MRI) in this region has revolutionized how we diagnose and treat horses with foot lameness.

Deep Digital Flexor Tendonitis/Tendonopathy Injury to the deep digital flexor tendon (DDFT) is a common soft tissue injury noted in horses with lameness that improves with PD analgesia. Lesions in the DDFT can occur in four locations or combinations, thereof: at the level of the pastern joint, just proximal to the navicular bone at the level of the collateral sesamoidean ligament, at the level of the navicular bone, and distal to the navicular bone at or near the tendon’s insertion on P38 (Figure 1).

A variety of treatment strategies have been recommended for DDFT injuries in the foot. Treatments typically consist of medication within the navicular bursa, coffin joint or systemic anti-inflammatories combined with corrective shoeing. Rest and controlled exercise was not historically recommended for horses that block to a PD; however with the knowledge gained from MRI, placing horses with DDFT injuries in a rest and controlled exercise program does seem to affect the prognosis.8,9 Lutter8 reported that a horse with DDFT injury is more likely to stay sound post -treatment with rest/rehabilitation +/- bursa injection compared to injection and returning to work. Horses that were rested — or rested and injected — remained sound for a median of 42 months (or 21 months, respectively) compared to just 12 months with just injection and returning to work. Overall, 33 percent of horses treated with both rest and injection, 28 percent with just rest and 15 percent with just injection were sound at follow up (median time to follow up was 5 years with an age range of 1 to 12 years old).

Arthroscopic examination of the navicular bursa has also been advocated for horses with DDFT injuries in the region of the proximal navicular bursa. Smith and Wright10 hypothesized that debridement of tendon lesions facilitates the development of an inert scar over the affected area. In their publication with

8 The Practitioner Issue 1 • 2019

Figure 1: Transverse MR images of a horse with deep digital flexor tendonitis at the level of the proximal navicular bursa (arrow). There is also fibrous tissue proliferation within the bursa adjacent to the area of tendonitis (arrowhead).

The other limb is included for comparison purposes.

92 horses, 63 percent of horses with follow up were sound and working. Horses with extensive DDFT tears were significantly less likely to be classified as sound and working (54 percent) compared with those with small tears (92 percent). The success rate certainly merits consideration as a possible treatment option.

Navicular Bursitis/Scar Tissue Formation In some horses, there will be marked distention of the proximal navicular bursa with very minimal synovial proliferation. These horses typically have a more acute lameness history and may also have concurrent injury to the DDFT and/or its dorsal border (Figure 1). In horses with acute (< six months) foot lameness that had MRI performed, 58 limbs had increased fluid in the navicular bursa, and 17 of the 58 limbs had marked increased fluid.11 Of the 17 limbs, 12 (71 percent) also had DDFT injury at the level of the bursa. Medication of the navicular bursa or navicular bursoscopy12 may be beneficial for these horses, and, typically, these horses have a better prognosis to return to full work free of lameness in the author’s experience.

The more common presentation are horses with marked fibrous proliferation with suspected scar tissue/adhesion formation, suggestive of a more chronic process. The adhesion formation may involve the dorsal border of the DDFT and/or the collateral sesamoidean ligament. Use of MRI has been shown to be useful in detection of these adhesions.12 In the author’s opinion, horses with large amounts of scar tissue/fibrous proliferation within the navicular bursa — to the point where normal navicular bursa fluid is difficult to identify — are more difficult to return to consistent work free of lameness either with medical therapy or surgery.

Collateral Sesamoidean Ligament Injury to the collateral sesamoidean ligament (CSL) can be considered the primary source of lameness, but, typically, it is noted in combination with other abnormalities in the navicular region. The author considers changes in this ligament to be the “canary in the coal mine” and a sign that abnormal forces have been WWW.FAEP.NET |

placed on the podotrochlear apparatus at some point. Sampson13 noted on the MR images that thickening, with or without abnormal hyperintensity, was noted in the CSL in 75 percent of horses with recent (< six months) onset of foot lameness and the primary abnormality in 11 of 72 (15 percent) horses. In horses with chronic (> six months) foot lameness, thickening — with or without hyperintensity — was observed in 91 percent of horses and the primary abnormality in 19 of 90 horses (24 percent).

Treatment for horses with injury to the CSL typically consists of anti-inflammatory medications within the coffin joint or navicular bursa along with corrective shoeing. Surgical transection of the CSL has also been reported.14,15

Collateral Ligaments of the Coffin Joint Injury to the collateral ligaments (CL) of the coffin joint should also be included on the differential list for soft tissue injuries that improve with a PD block. Determining the clinical significance of most CL injuries can be problematic due to the location of the CL. Except for the proximal portion, most of the ligament is within the hoof capsule. Due to the fact that most of the ligament is difficult to image with ultrasound, injury to the CL is primarily an MRI diagnosis; however, interpretation of injuries to the CL is also difficult even with the use of MRI because of magic angle artifact and positioning.16 The author believes that false positive results, as well as false negatives, of injury to the CL of the coffin joint are somewhat common with MRI, particularly if the changes are mild or if the horse has biaxial injury. Correlation to the clinical presentation along with more specific blocking may help determine the clinical significance of MRI findings in the CLs. In the author’s opinion, lesions in the distal aspect of the CL typically improve to some degree with a PD block (Figure 2). In addition, most horses with clinical injury to the CL will have increased fluid present in the coffin joint, yet this may not be the case if the horse has a recent history of anti-inflammatory injection within the coffin joint.

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Figure 2: Transverse fat-suppressed and representative sagittal image — representing the level of the transverse image — of a horse with marked injury to the medial collateral ligament of the coffin joint (arrow), along with osseous injury at the ligament’s attachment (arrowhead).

Other Options Based on the results of MRI in horses that block to a PD, further localization can then be performed with intra-articular, intrathecal or intra-bursal anesthesia. In addition, if the horse cannot have an MRI performed, a greater amount of information can be gleaned from more specific anesthesia. It is important to note the lack of specificity of coffin joint anesthesia due to the diffusion of anesthetic. It has been recommended that in order to minimize the diffusion into the navicular bursa, 5-6 mls of anesthetic should be placed in the coffin joint and the response assessed after five to 10 minutes.17 Interestingly, placing anesthetic in the navicular bursa does not usually cause anesthesia of the coffin joint if the horse is examined within 20 minutes of the block;18 thus, anesthesia of the navicular bursa may be more specific than the coffin joint.

Anesthesia of the digital flexor tendon sheath is often overlooked as a block that may help to sort out lameness in the foot. The digital sheath extends distally into the hoof and is adjacent to the proximal palmar pouch of the coffin joint as well as the proximal navicular bursa. Horses with injuries to the deep digital flexor in the foot that extend proximal to the navicular bursa will respond to analgesia of the tendon sheath. It is important to note that leaking of the anesthetic from the injection site may occur; thus, the palmar digital nerves may be blocked.19 In conclusion, there are numerous soft tissue injuries in the foot where lameness is improved with a PD nerve block. It is important to recognize the limitations of a PD nerve block, along with how knowledge gained from MRI and the results of intrasynovial analgesia correlated to imaging findings help to arrive at an accurate diagnosis.

References

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11.

Schumacher J, Steiger R, Schumacher J, et al. Effects of analgesia of the distal interphalangeal joint or palmar digital nerves on lameness caused by solar pain in horses. Vet Surg 2000;29:54-58.

Easter JL, Watkins JP, Stephens SL, et al. Effects of regional anesthesia on experimentally induced coffin joint synovitis, in Proceedings. Am Assoc Equine Pract 2000;46:214-216.

Schumacher J, Livesey L, de Graves FJ, et al. Effect of anaesthesia of the palmar digital nerves on proximal interphalangeal joint pain in the horse. Equine Vet J 2004;36:409-415.

Nagy A, Malton R. Diffusion of radiodense contrast medium after perineural injection of the palmar digital nerves. Equine Vet Edu 2015;27:648-654.

King JN, Zubrod CJ, Schneider RK, et al. MRI findings in 232 horses with lameness localized to the metacarpo(tarso) phalangeal region and without a radiographic diagnosis. Vet Radiol Ultrasound 2013;54:36-47.

Cohen JM, Schneider RK, Zubrod CJ, et al. Desmitis of the distal digital annular ligament in seven horses: MRI diagnosis and surgical treatment. Vet Surg 2008;37:336-344.

Sampson SN, Schneider RK, Tucker RL, et al. Magnetic resonance imaging features of oblique and straight distal sesamoidean desmitis in 27 horses. Vet Radiol Ultrasound 2007;48:303-311.

Lutter JD, Schneider RK, Sampson SN, et al. Medical treatment of horses with deep digital flexor tendon injuries diagnosed with high-field strength magnetic resonance imaging: 118 cases (20002010). J Am Vet Med Assoc 2015;247:309-1318.

Marsh CA, Schneider RK, Sampson SN, et al. Response to injection of the navicular bursa with corticosteroid and hyaluronan following high-field magnetic resonance imaging in horses with signs of navicular synodrome: 101 cases (20002008). J Am Vet Med Assoc 2012;241:1353-1364.

Smith MRW, Wright IM. Endoscopic evaluation of the navicular bursa: observations, treatment and outcome in 92 cases with identified pathology. Equine Vet J 2012;44:339-345.

Sampson SN, Schneider RK, Gavin PR, et al. Magnetic resonance imaging findings in horses with recent onset navicular syndrome but without radiographic abnormalities. Vet Radiol Ultrasound

10 The Practitioner Issue 1 • 2019

2009;50:339-346.

12. Holowinski ME, Solano M, Maranda L, et al. Magnetic resonance imaging of navicular bursa adhesions. Vet Radiol Ultrasound 2012;53:566-572.

13. Sampson SN, Schneider RK, Gavin PR. Magnetic resonance imaging findings in horses with recent and chronic bilateral forelimb lameness diagnosed as navicular syndrome, in Proceedings. Am Assoc Equine Pract 2008;54:419-434.

14. Sampson SN, Schneider RK, Gavin PR, et al. Evaluation of an arthroscopic approach for transection of the equine collateral sesamoidean ligament. Vet Surg 2010;39:1011-1020.

15. Wright IM. A study of 118 cases of navicular disease: treatment by navicular suspensory desmotomy. Equine Vet J 1993;25:501-509.

16. Gutierrez-Nibeyro SD, Werpy NM, White NA, et al. Standing low-field magnetic resonance imaging appearance of normal collateral ligaments of the equine distal interphalangeal joint.

Vet Radiol Ultrasound 2011;52:521-533.

17. Pleasant RS, Moll HD, Ley WB, et al. Intraarticular anesthesia of the distal interphalangeal joint alleviates lameness associated with the navicular bursa in horses Vet Surg 1997;26:137-140.

18. Schumacher J, Schumacher J, Gillette R, et al. The effects of local anaesthetic solution in the navicular bursa of horses with lameness caused by distal interphalangeal joint pain. Equine Vet J 2003;35: 502-505.

19. Jordana M, Martens A, Duchateau L, et al. Distal limb desensitization following analgesia of the digital flexor tendon sheath in horses using four different techniques. Equine Vet J 2014;46:488-493.

Matthew Brokken, DVM, DACVS, DACVSMR Dr. Matthew Brokken is an associate professor at The Ohio State University College of Veterinary Medicine. He is a 2003 graduate from the University of Florida and completed an equine ambulatory internship at The Ohio State University in 2004 and an equine surgery residency at Washington State University in 2007. After residency, Dr. Brokken was faculty at the University of Florida and was head of the newly formed Lameness and Imaging Service.

In 2010, Dr. Brokken transitioned to private practice and was a staff surgeon at Cleveland Equine Clinic in Ravenna, Ohio until he returned to Ohio State in 2012.

Dr. Brokken is a diplomate of the American College of Veterinary Surgeons, as well as the American College of Veterinary Sports Medicine and Rehabilitation. He specializes in performance-limiting lameness, orthopedic surgery, and advanced imaging (specifically equine MRI).

Dr. Brokken has a particular interest in the diagnosis and management of hindlimb proximal suspensory injury.

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LARYNGOPLASTY AND LARYNGOPLASTY COMPLICATIONS JOHN B. MADISON | VMD, DACVS

In the past 20 years regarding the subject of laryngoplasty, much work has been done on the technique, yet very little has changed that impacts the way laryngeal hemiplegia (ILH) is treated today compared to two decades ago. In fact, the technique remains largely unchanged from the original procedure described by Marks 50 years ago.1 Improvements have clearly been made in the diagnosis of laryngeal hemiplegia, initially with the advent of high-speed treadmill endoscopy (HSTM) which has now been replaced with over the ground endoscopy (OTGE). Still, the majority of cases of ILH are diagnosed using resting endoscopy with nasal occlusion.

Only those cases with borderline — or sometimes normal — findings on resting endoscopy require further evaluation with OTGE. Over the ground endoscopy has proved useful not only in separating resting grade 3a from grade 3b horses but in also detecting horses with completely normal resting endoscopy that dynamically collapse the left arytenoid during exercise. Over the ground endoscopy has also provided additional valuable information on possible postoperative complications following laryngoplasty,2 although some questions exist regarding the degree of arytenoid abduction in the test populations.

Laryngeal palpation remains a valuable skill to detect CAD muscle atrophy; however, this is becoming somewhat supplanted by the increasing use of ultrasound examinations to provide the same but possibly less subjective information in detecting muscle atrophy in routine cases of left-sided ILH. Ultrasound evaluation is particularly helpful in cases of right-sided paralysis.

Fourth branchial arch defects must be ruled out in all cases of right-sided paralysis, and this often can be done with an ultrasound evaluation of the larynx.3 The primary abnormalities seen are the lack of a right cricothyroid articulation, the right thyroid cartilage extending dorsal to the muscular process, and the presence of the right cricoarytenoideus lateralis muscle in an abnormal space between the thyroid and cricoid cartilages.

Likewise, ultrasound evaluation of the larynx is able to detect arytenoid chondritis.4 The primary abnormalities seen in affected cartilages are an increase in arytenoid cross sectional area, an abnormal shape of the arytenoid and increased echogenicity in the arytenoid cartilage. In addition, we are seeing more cases of pre- and post-operative ventral deviation of the apex of the corniculate process with OTGE than we have seen with HSTM endoscopy.

Recently, there has been fairly widespread, although not universal, acceptance of a modified technique that promotes ankylosis of the cricoarytenoid joint.5 There are clearly some advantages to the technique with regard to the prevention of long term loss of abduction following laryngoplasty. A serious shortcoming of the technique, however, is the fusion of the CA joint in a horse in which there has been early loss of abduction or inadequate abduction at the time of surgery. This results in an inability to abduct the arytenoid at a second surgery. Unfortunately, it is often difficult or impossible to find out if the CA joint has been previously ankylosed in horses presented for repeat laryngoplasty.

It is frustrating for the surgeon tasked with trying to re-abduct a failed laryngoplasty and expensive for the owner when the repeat tie back is unsuccessful and the only option remaining is partial arytenoidectomy. While I have given strong consideration to adopting the technique, the long-term failure rate is so low that in my caseload I don’t think the procedure is warranted. Most laryngoplasty failures occur within the first month and probably within the first couple of weeks, so — in my opinion — surgeons performing this technique should be aggressive in re-scoping the horse in the first few weeks after surgery so that if there is early loss of abduction there is still an opportunity to correct the problem without resorting to arytenoidectomy.

Several recent papers have illustrated the importance of the accuracy of suture placement in achieving maximal arytenoid abduction. In a paper examining the optimal placement of nervemuscle pedicle grafts for the treatment of ILH in the medial and lateral neuromuscular compartments of the cricoarytenoideus dorsalis (CAD), equal forces were applied to the muscular process at varying angles from 0o to 70o and the angles which provided the most arytenoid abduction were determined. It was found that forces applied at angles between 0o to 30o — corresponding to the lateral compartment of the CAD — provided greater abduction than forces applied between 40o to 70o — corresponding to the medial compartment of the CAD.6 Maximal abduction was achieved at an angle of 30o. This study has important implications for the performance of LP in that the optimal angle for suture placement is along the 30o axis. Two additional studies examined the effect of the number and position of sutures on the rima glottidis area in cadaver larynges.7,8 In these studies, it was found that the area of the rima glottidis was greater when two sutures placed along the 20o and 30o axes were tied compared to the area achieved when the sutures were tied individually. It is important to note that in this study the suture bites through the muscular

16 The Practitioner Issue 1 • 2019

When assessing the postoperative appearance of a tie back, the larynx should be examined at rest (left photograph) and with maximal abduction of the opposite (right) arytenoid (right photograph). In the author's opinion, the ideal amount of abduction of the left arytenoid is for it to match the right arytenoid at maximal abduction during nasal occlusion. process were perpendicular to the axis of the CA joint. Similar vector forces could be achieved using a single suture placed parallel to the CA joint. These studies point out how even slight variations in suture placement can make a significant difference in the area of the rima glottidis. It is important to realize that the cricoartytenoideus lateralis (CAL) originates only 90 degrees from the CAD muscle, so the further lateral the sutures are placed on the cricoid the more adduction is obtained. I have used for many years a No. 3 nylon suture and a No. 5 Ethibond suture with both sutures placed on the midline of the cricoid and at slightly different angles on the muscular process roughly parallel to the CA joint. The nylon suture is tied first and allows the back side of the Ethibond suture to be tightened before it is tied. Using this combination of suture material prevents the early loss of abduction seen when the surgeon is unable to tighten the back side of the suture because of tissue drag on braided polyester.

There is a trend (and not a good one in my opinion) in equine surgery to try to perform more and more procedures standing, and laryngoplasty has not been forgotten. At a time when anesthesia has never been safer, a technique for standing laryngoplasty has been described.9 While this technique may be an important advance in treating ILH in draft horses, the use of standing laryngoplasty in light horses is, in my opinion, questionable at best. Laryngoplasty is a difficult enough technique to perform under anesthesia so there would have to be some pressing need to perform the procedure standing for the author to consider it worthwhile. The authors, however, were able to achieve good or moderate abduction in most horses.

There are still a variety of widely held beliefs surrounding the diagnosis and management of horses with ILH that need to be revisited. These include dogma regarding case selection, the degree of abduction that should be obtained at surgery, and the causes of postoperative coughing and aspiration.

The belief that horses should be allowed to become completely paralyzed before performing laryngoplasty is still widely held

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among veterinarians despite the fact that there is no evidence to support this assumption, and there is now, in fact, evidence to the contrary. This assumption arose from the belief many years ago that suture failure following laryngoplasty was presumed to be more likely if there was still movement (grade 3) when compared to horses that were completely paralyzed (grade 4) due to repeated cycling of the sutures. Twenty years ago, I suggested that there was little logic or evidence to support this assumption.

First, it is logical to expect that suture failure caused by residual movement of the arytenoid would be more likely to be caused by adduction rather than continued abduction. It has been shown that adductor function is generally lost before abductor function in naturally occurring cases of ILH.10,11 The apparent lack of improvement in the failure rate when recurrent laryngeal neurectomy was performed in conjunction with laryngoplasty,12 as well as the similar success rates reported previously for horses with grade 3 and grade 4 ILH,13 supported the belief that there was no evidence to justify the widely held dogma that horses should not be operated on until they were completely paralyzed.

Since that time, another retrospective study has been published that demonstrated that Thoroughbred horses that were operated on when they had grade 3 function actually performed better (more postoperative earnings) than horses that underwent surgery when their laryngeal function was grade 4.14 It has also been my clinical impression that it is sometimes more difficult to achieve maximal abduction of the arytenoid in grade 4 horses.

So what are my case selection criteria? Any horse that is showing signs of exercise intolerance with any grade of ILH, including those with normal resting function that dynamically collapse the left arytenoid on OTGE, is a candidate for laryngoplasty.

There is, however, no point in performing the surgery very early in training or as a yearling before the horse begins to train. I generally recommend that the horse be trained until it begins to demonstrate exercise intolerance. This usually occurs after the horse starts breezing one quarter to a half mile although some horses will show evidence of exercise intolerance much earlier in their training. My goal is to get the horse well into

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their training program but not push them so hard that they begin to lose confidence in their ability to finish their work without becoming distressed. There is a condition in human athletes termed anticipatory regulation where the brain regulates the pace of exercise based on the integration of signals from various physiologic systems. I suspect that this also occurs in the horse, and it can be difficult to “train out” of a horse once established.

This early training allows the trainer some assessment of the horse’s ability and hopefully increases the confidence that the limiting factor in the horse’s ability to perform is, in fact, ILH. I think most surgeons are now aware that there is no need to wait for a horse to become completely paralyzed. In fact, there may be a disadvantage in waiting that long; however, there is a whole generation of veterinarians that were taught otherwise that are still advising clients to wait for horses to become completely paralyzed. As a profession, we still have some work to do to educate our colleagues that the old dogma is no longer considered accurate.

The second dogma regarding laryngoplasty that I think needs to be revisited is the cause(s) of postoperative coughing and aspiration. Coughing and aspiration can be seen with all degrees of arytenoid cartilage abduction from hyperabduction to no abduction at all. It has been my contention for many years that tension on the sutures, and not the degree of abduction, is the major contributor to postoperative coughing. There are probably also some other less common reasons for coughing like loss of laryngeal sensation secondary to damage to the cranial laryngeal nerve or damage to the upper esophageal sphincter,15 but the predominate cause appears to be related to the presence of the laryngoplasty sutures. The hypothesis that tension on the sutures is the predominate cause of coughing is based on three clinical observations. First, suture removal nearly always immediately resolves the coughing and aspiration, even in those cases where arytenoid abduction is maintained by scar tissue or CA joint ankylosis. Second, I have on a number of occasions removed and replaced the sutures in horses that are aspirating, achieved

more abduction than was present prior to surgery, and have the coughing stop following the repeat laryngoplasty. Finally, as mentioned earlier, coughing and aspiration can occur even in horses with no arytenoid abduction. If the sutures are placed under a lot of tension in an effort to achieve abduction, the horse may cough regardless of the degree of abduction.

From a client communication standpoint, it is frustrating and, frankly, of no benefit to anyone involved when the referring veterinarian tells the client that the coughing is caused by the arytenoid being overabducted. A more appropriate response, in my opinion, would be something along the lines of: “Your horse is experiencing a common complication that occurs following tie back surgery because a portion of the mechanism to keep food and water out of the airway has been disabled. Your horse may need to have the sutures removed or loosened.”

Finally, the issue of how much arytenoid abduction is optimal needs to be revisited. It is widely believed that optimal abduction is somewhere less than maximal abduction. I think that there is evidence to suggest that anything less than maximal abduction causes secondary post-laryngoplasty dynamic airway problems.

Admittedly from an owner’s perspective, sport horses can frequently perform well with less than maximal abduction. I’m not at all sure that racehorses will perform to their ability with less than maximal abduction. I personally strive to abduct the left arytenoid to a position that matches the right arytenoid at full abduction in all cases regardless of use. In a racehorse, anything worse than Dixon grade 2 (high degree of abduction) may lead to impaired performance.

A HSTM study looked at 45 horses with respiratory noise or poor performance following larygnoplasty and a variety of dynamic abnormalities were found including left arytenoid collapse, left and right vocal fold billowing, AE fold collapse, DDSP, ventral deviation of the apex of the left corniculate process, and pharyngeal collapse. Collapse of more than one structure was observed in most examinations. What struck me about this study is that no horse was abducted better than Dixon

The right image shows the preoperative appearance of the larynx. The left photo shows the larynx after injection of PMMA into remnant of left vocal fold.

18 The Practitioner Issue 1 • 2019

grade 3.16 A more recent OTGE study of 41 horses following laryngoplasty demonstrated very similar results with multiple dynamic abnormalities observed.2 In that paper, the degree of abduction ranged from Dixon grade 2 to 5 with a mean degree of abduction of grade 3. Again, it appears that anything worse than grade 2 abduction leads to increased impedance and subsequent collapse of other airway structures during exercise. In an in vitro computational flow model that looked at 100 percent, 88 percent and 75 percent abduction, anything less than maximal abduction resulted in increased negative pressure in the airway.15 The take-home message is that intermediate abduction of the left arytenoid following laryngoplasty results in a high incidence of postoperative dynamic airway problems.

Left-sided laser ventriculocordectomy is performed in conjunction with the laryngoplasty in all cases. The benefits on airway mechanics are minimal; however, the procedure will prevent dynamic collapse of the left vocal fold in the small population of horses that continue to collapse their vocal fold after a successful laryngoplasty. As a sole procedure to treat exercise intolerance, laser ventriculocordectomy is probably useless and simply postpones the inevitable laryngoplasty. It is of some use as a standalone procedure in eliminating noise in a relatively low percentage of horses that are not exercise intolerant (hunters).

The prognosis for a successful outcome following laryngoplasty is highly variable, depending on the intended use of the horse and the experience of the surgeon. Between 60 to 70 percent of racehorses will perform successfully, and the success rate in sport horses approaches 90 percent.

LARYNGOPLASTY COMPLICATIONS

Laryngoplasty (LP) is a procedure that has been plagued by complications since its inception nearly 50 years ago. Shortterm complications, like intra-operative hemorrhage, seroma formation and wound infections, are not unique to LP and are similar to what may be experienced with any surgical procedure and are managed as they would be with any procedure. Intraoperative hemorrhage often occurs when the cranial thyroid artery or vein are penetrated during placement of the cricoid bite of the LP suture. Hemorrhage will invariably persist until the first LP suture is tied, and the hemorrhage will then stop. Seroma formation should occur in less than 10 percent of cases and most commonly requires no treatment. If there is drainage of serum through the incision, one or two sutures may be removed to drain the seroma. Superficial wound infections that do not involve the LP sutures can be managed with drainage and antimicrobials.

Infection of the LP sutures themselves should be an extremely uncommon complication and is usually due to penetration of the laryngeal lumen during placement of the LP sutures. If penetration is recognized intra-operatively, the suture should be removed, the surgery site lavaged and a new suture placed.

If, however, infection of the sutures develops as a postoperative complication, the infected sutures should be removed.

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Longer term and more difficult complications tend to fall into three basic categories: loss of abduction, coughing and aspiration, and dynamic collapse of laryngeal structures post-LP. Other far less common long-term complications include arytenoid chondropathy after LP and atrophy of the corniculate process.

Loss of Abduction

Loss of abduction is the most common and frustrating complication of LP. Swallowing, vocalization and coughing all exert tension on the LP sutures and may contribute to postoperative loss of LP abduction.17 Pressure necrosis of the arytenoid and cricoid cartilages from tension on the sutures may cause the sutures to loosen resulting in abduction loss. There are intrinsic individual horse factors that are out of the control of the surgeon that play a role in either the ability to achieve maximal abduction at the time of surgery or in the early and late loss of abduction after surgery. These include: 1. The size of the muscular process (length of the lever arm).

2. Toughness of the laryngeal cartilages, especially the muscular process.

3. Anatomy of the cricoid (extremely variable, distinct median notch and long thin caudal cartilage margin).18 4. Possible unrecognized arytenoid enlargement from a previous episode of arytenoid chondritis.

The extrinsic- or surgeon-controlled factors that influence the ability to achieve and maintain abduction include: 1. Suture placement.

2. Suture material.

3. Cricoarytenoid joint fusion.5 Suture placement is far and away the most important factor within the control of the surgeon that influences the ability to achieve and maintain abduction. Cricoarytenoid joint fusion does prevent long-term loss of abduction, but it does not prevent short-term loss of abduction. In a study of quarterly earnings in 70 Thoroughbreds post-LP, there was no loss of earning potential over time, and 100 percent of horses having the procedure raced.19 One of the disadvantages of this technique is that unrecognized short-term loss of abduction can result in fusion of the cricoarytenoid joint with the arytenoid in an inadequately abducted position. The majority of horses that lose abduction do so within the first six weeks and most probably within the first two weeks after surgery. The goals of suture placement are to: 1. Achieve maximal abduction by placing sutures so the suture direction mimics the optimal vectors for abduction of the arytenoid.

2. Ensure adequate size of suture bites through the cricoid and muscular process.

3. Maximize the amount of muscular process lever arm while ensuring adequate toughness of cartilage where the sutures are placed.

4. Use of one monofilament suture for the suture that is tied first to ensure that the back side of the second suture is pulled tight before tying.

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The author places a No. 3 polypropylene suture and a No. 5 braided polyester suture on the midline of the cricoid cartilage and then from rostromedial to caudolateral through the muscular process (roughly parallel to the cricoarytenoid joint). Placement of the sutures in this fashion results in the vector alignment of both arms of the suture closely approximating the 10o to 30o vectors of the lateral compartment of the cricoarytenoideus dorsalis muscle, which results in the most abduction of the arytenoid.6, 7, 8 The monofilament suture is tied first to fully abduct the arytenoid allowing the back side of the polyester suture to be pulled tight before tying. This technique prevents early loss of abduction that can occur when the surgeon is unable to tighten the back side of a braided suture because of tissue drag when the suture ends are pulled at an angle to the direction of penetration of the muscular process.

Coughing and Aspiration

Coughing and aspiration of food and water are common complications after LP. Estimates range from 6 percent to as high as 40 percent of horses experiencing some degree of coughing after surgery. The causes of post-LP coughing are poorly understood, and there are likely several potential causes.

Overabduction of the arytenoid is the most commonly cited reason for post-LP dysphagia; however, there is little evidence to incriminate this as the primary cause. In fact, recent evidence sheds doubt on the degree of abduction as being the major contributor to postoperative coughing and aspiration. There is clearly no direct correlation between the degree of abduction and the incidence of aspiration. As previously mentioned, coughing and aspiration can be seen with all degrees of arytenoid cartilage abduction from hyperabduction to no abduction at all. The hypothesis that tension on the sutures is the predominate cause of coughing is based on three clinical observations. First, suture removal nearly always immediately resolves the coughing and aspiration, even in those cases where arytenoid abduction is maintained by scar tissue or CA joint ankylosis. Second, I have on a number of occasions removed and replaced the sutures in horses that are aspirating, achieved more abduction than was present prior to surgery, and have the coughing stop following the repeat laryngoplasty. Finally, as mentioned earlier, coughing and aspiration can occur even in horses with no arytenoid abduction. If the sutures are placed under a lot of tension in an effort to achieve abduction the horse may cough regardless of the degree of abduction.

The persistence of long-term coughing and aspiration can have significant negative consequences on the horse.20 Chronic dysphagia can result in lower airway disease ranging from mild bronchitis to severe and even potentially fatal pneumonia. Longterm aspiration can lead to performance-limiting lower airway problems. From a surgical perspective, until there is a significant paradigm shift in how we deal with laryngeal hemiplegia, careful dissection minimizing damage to the perilaryngeal muscles and nerves and achieving maximal abduction with minimal tension (e.g. optimal suture placement) are all that can be done to minimize this complication.

Treatment options for horses experiencing significant aspiration and dysphagia are removal or loosening of the LP sutures. More recently, vocal fold bulking with PMMA has been a very effective technique for stopping aspiration in some horses.

Post-laryngoplasty Dynamic Abnormalities

In the last 10 years, several dynamic studies have been done on postoperative LP patients. A high-speed treadmill study looked at 45 horses with respiratory noise or poor performance following larygnoplasty and a variety of dynamic abnormalities were found including left arytenoid collapse, left and right vocal fold billowing, AE fold collapse, DDSP, ventral deviation of the apex of the left corniculate process, and pharyngeal collapse. Collapse of more than one structure was observed in most examinations.

What struck me about this study is that no horse was abducted better than Dixon grade 3.16 Another resting and over the ground endoscopic (OTGE) study looked at the long-term maintenance of arytenoid cartilage abduction in 33 horses of varying breeds and uses.21 In that study, the mean Dixon abduction grade was 2 at one week post-op and grade 3 at six weeks post-op. Most, but not all, horses maintained their degree of abduction from the six-week resting evaluation to the time of an exercising over the ground evaluation done a mean of 33 months after the surgery (range four to 71 months).

Despite significant loss of abduction, arytenoid stability during exercise was maintained in 26 of 33 horses. It should be noted, however, that only seven horses in this study were racehorses.

Although all horses were exercised at maximal exertion for their intended use, only the racehorses were likely to have been examined under conditions resulting in maximal airflows. The incidence of arytenoid instability may have been underestimated because of the low number of racehorses in this study.

Another OTGE study of 41 horses following laryngoplasty demonstrated dynamic abnormalities in 78 percent of the horses examined (32 of 41) with 41 percent having multiple dynamic abnormalities.2 In that paper, the degree of abduction ranged from Dixon grade 2 to 5 with a mean degree of abduction of grade 3. Despite these findings, 93 percent of the owners reported the surgery to be beneficial on a questionnaire.

A third prospective OTGE study looked at the pre- and postoperative dynamic exam findings in 35 Thoroughbred racehorses a mean of six months after LP.22 These horses had LP and ventriculocordectomy performed via laryngotomy. The mean resting Dixon abduction grade at the postoperative exam was 3 (range 2-5). The following results were found on the OTGE exam: 23 percent had vocal cord collapse, 48 percent had axial deviation of the AE folds (most right-sided only), 17 percent had ventral deviation of the apex of the corniculate process, and one horse (3 percent) displaced the soft palate.

One of two conclusions can be drawn from the results of these studies: Either dynamic abnormalities are a common complication of LP surgery, or arytenoid abduction Dixon

20 The Practitioner Issue 1 • 2019

2. Barnett TP, O’Leary JM, Parkin TDH, Dixon PM, Barakzai SZ: Long-term exercising video-endoscopic examination of the upper airway following laryngoplasty surgery: A prospective crosssectional study of 41 horses. Eq Vet J 45:593-597, 2013 3. Garrett KS, Woodie JB, Embertson RM, Pease AP: Diagnosis of laryngeal dysplasia in five horses using magnetic resonance imaging and ultrasonography. Eq Vet J 41:766-771,2009.

4. Garrett KS, Embertson RM, Woodie JB, Cheetham J: Ultrasound features of artenoid chondritis in Thoroughbred horses. Eq Vet J 45:598-603,2012.

5. Parente EJ, Birks EK, Habecker P: A modified laryngoplasty approach promoting ankylosis of the cricoarytenoid joint. Vet Surg 40:204-210, 2011.

6. Cramp P, Derkesen FJ, Stick JA, DeFeijter-Rupp H, Elvin NG, Hauptman J, Robinson E: Effect of magnitude and direction of force on laryngeal abduction: Implications for the nerve-muscle pedicle graft technique. Eq Vet J 41:328-333 (2009).

7. Dart A, Tee E, Brennan M, Dart C, Perkins N, Chapman S, Debney S: Effect of prosthesis number and position on rima glottidis area in equine laryngeal specimens. Vet Surg 38:452256 (2009).

While it would be interesting to perform dynamic exams on this population of horses, finances are directed toward trying to 8. Bischofberger AS, Wereszka MM, Hadidane I, Perkins NR, Jeffcott LB, Dart AJ: Optimal tension, position, and number correct the loss of abduction. The only horses that typically get of protheses required for maximal rima glottidis area after exercising endoscopy post-LP are the very small population of larygnoplasty. Vet Surg 42: 280-288 (2013). horses that are either making a noise or are exercise intolerant 9. Rossignol F, Vitte A, Boening J, Maher M, Lechartier A, despite maximal abduction of the left arytenoid. In nearly all Brandenberger O, Martin-Flores M, Lang H, Walker W, these cases, the dynamic abnormality causing the impaired Ducharme NG: Laryngoplsty in standing horses. Vet Surg 44:341airflow is ventral deviation of the apex (VDAC) of the left 347,2015. corniculate process. It is interesting to note that in the study by 10. Duncan ID, Amundson J, Cuddon R, Sufit R, Jackson KF, Lindsay Leutton and Lumsden, only two of 35 horses exhibited VDAC WA: Preferential denervation of the adductor muscles of the pre operatively, while six of 35 exhibited the problem after LP. equine larynx I: muscle pathology. Eq Vet J 23:94-98, 1991.

It has been my observation as well that LP seems to predispose 11. Duncan ID, Reifenrath P, Jackson KF, Clayton M: Preferential denervation of the adductor muscles of the equine larynx II: some horses to develop this problem. Interestingly, two of the 21,22 nerve pathology. Eq Vet J 23:00-103, 1991. long-term dynamic studies found no correlation between the 12.

Davenport CLM, Tulleners EP, Parente EJ: The effect of recurrent degree of abduction and the presence of food material in the laryngeal neurectomy in conjunction with laryngoplasty and upper airway similar to observations made by others on resting unilateral ventriculocordectomy in Thoroughbred racehorses. endoscopy.

Vet Surg 30: 417-421, 2001.

13. Hawkins JF, Tulleners EP, Ross MW, Evans LH, Raker CWL: Despite the abundance of potential complications following the Laryngoplasty with or without ventriculocordectomy for procedure, laryngoplasty remains the current best treatment treatment of left laryngeal hemiplegia in 230 racehorses. Vet for management of horses with laryngeal hemiplegia. Many Surg 26: 484-491, 1997. variations of the procedure have been examined, primarily to 14. Witte TH, Mohammed HO, Radcliffe CH, Hackett RP, Ducharme NG: Racing performance after combined prosthetic laryngoplasty prevent loss of abduction; however with the possible exception and ipsilateral ventriculocordectomy or partial arytenoidectomy: of fusion of the CA joint, the procedure, in principle, remains 135 Thoroughbred racehorses competing at less than 2400 m largely unchanged from the procedure described by Marks 48 (1997-2007).

Eq Vet J 41: 770-775, 2009. years ago. A number of questions remain unanswered despite 15.

Barakzai SZ, Dixon PM, Hawkes CS Cos A, Barnett TP: nearly 50 years of performing this procedure. The effect of Upper esophageal incompetence in five horses after prosthetic the degree of abduction on performance and the presence of laryngoplasty. Eq Vet J 44: 150-155, 2014. postoperative dynamic problems remains an open question. 16. Davidson EJ, Martin BB, Reiger RH, Parente EJ: Exercising Likewise, there are currently no good theories for the cause of videoendoscopic evaluation of 45 horses with respiratory noise ventral deviation of the apex of the corniculate process either preand/or poor performance after laryngoplasty. Vet Surg 39: 942or post-laryngoplasty and methods to manage the problem have 948, 2010. yet to be validated.

17. Witte TH, Cheetham J, Soderholm LV, Mitchell LM, Ducharme NG: Equine laryngoplasty sutures undergo increased loading during coughing and swallowing. Vet Surg 39:949-956 (2010).

References 1. Marks D, Mackay-Smith MP, Cushing LS, Leslie JA: Prosthetic 18. Dahlberg JA, Valdes-Martinez A, Boston RC, Parente EJ: Analysis of conformational variations of the cricoid cartilages device for surgical correction of laryngeal hemiplegia in horses. in Thoroughbred horses using computed tomography. Eq Vet J J Am Vet Med Assoc 157:157-163, 1970 43:229-234 (2011).

grade 3 or higher leads to increased impedance and subsequent collapse of other airway structures during exercise. If you believe, as I do, that intermediate abduction leads to postoperative dynamic complications then the implication is that we should be striving for maintenance of maximal arytenoid abduction (e.g. matches right-sided abduction at full abduction). In an in vitro computational flow model that looked at 100 percent, 88 percent and 75 percent abduction, anything less than maximal abduction resulted in increased negative pressure in the airway.23 Until similar long- or short-term dynamic exercising evaluations of horses with maximally abducted arytenoids have been performed, the assertion that intermediate abduction of the left arytenoid following laryngoplasty results in a high incidence of postoperative dynamic airway problems remains a hypothesis.

In the author’s practice, horses exhibiting exercise intolerance and a noise after a tie back are considered failed tie backs if they are Dixon grade 3 or higher.

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@FLORIDA_VMA | The Practitioner 21

19. Aceto H, and Parente EJ: Using quarterly earnings to assess racing performance in 70 thoroughbreds after modified laryngoplasty for treatment of recurrent laryngeal neuropathy. Vet Surg 41:4954, (2012).

20. Mason BJ, Riggs CM, Cogger N: Cohort study examining longterm respiratory health, career duration, and racing performance in racehorses that undergo left-sided prosthetic laryngoplasty and ventriculocordectomy surgery for treatment of left-sided laryngeal hemiplegia. Eq Vet J 45:229-234 (2013).

21. Barnett TP, O’Leary JM, Parkin TDH, Dixon PM, Barakzai SZ: Long-term maintenance of arytenoid cartilage abduction and stability during exercise after laryngoplasty in 33 horses. Vet Surg 42:291-296 (2013).

22. Leutton JL and Lumsden JM: Dynamic respiratory endoscopic findings pre- and post larygnoplasty in Thoroughbred racehorses.

Eq Vet J 47:531-536 (2015).

23. Rakesh V, Ducharme NG, Cheetham J, Datta AK, Pease qp: Implications of different degrees of arytenoid cartilage abduction on equine upper airway characteristics. Eq Vet J 40:629-635 (2008).

John B. Madison VMD, DACVS Ocala Equine Hospital, PA Dr. John Madison is a 1981 graduate of the University of Pennsylvania School of Veterinary Medicine. He did an internship and surgery residency at New Bolton Center, and he remained at New Bolton as a lecturer until joining the faculty of the University of Florida in 1989. He left the University of Florida in 1997 and opened Ocala Equine Hospital, a referral equine surgical practice. The surgical practice merged with two ambulatory practices in 2001 as the current Ocala Equine Hospital, PA. Dr. Madison is an avid hockey player and woodworker.

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Mental Health and Well-being in the Veterinary Profession Samantha Rosenthal, FVMA Communications Dr. Richmond explains that one of the first steps of understanding this issue is knowing what exactly it means when we talk about wellness and well-being, because often veterinarians aren’t aware it is inclusive of much more than our mental health. When we refer to wellness, it encompasses the care and value we place on our bodies, including eating right, keeping an active lifestyle, staying hydrated and making sure we’re getting enough sleep. The concept of well-being refers more to an individual’s emotional, spiritual and mental health on a day-to-day basis.

In recent years, there has been a growing concern regarding mental health across the entire medical profession. This issue has also started to gain awareness within the veterinary profession, with increased research and conversations about mental distress and suicide within the population.

As the profession continues to invest time into exploring this issue, many organizations like the AVMA, FVMA and other veterinary groups worldwide have started to incorporate wellness and well-being into their missions with a focus to help bring about a positive impact for mental health in veterinary medicine.

The FVMA spoke with some of its members who are a part of this movement of bringing the current state of mental health in veterinary medicine to the forefront of people’s minds. Many of these individuals have experienced mental distress at points in their career. They’re now using their experiences and expertise to help others who might be experiencing these issues relearn how to enjoy and love their veterinary careers, and educate veterinary students who are about to start their professional journeys.

The Current State of Mental Health in the Profession

While it may not have always been talked about, distress and concerns for wellness have been issues that the veterinary profession has had for years. Veterinarians are often faced with the task of balancing the needs of their patients and clients alongside what medically and/or biologically can or can’t be done. The compounding stress of knowing what can and can’t be provided to a patient based on certain limitations – whether that be financial or client preferences – has been an ongoing battle with veterinarians across the country and worldwide.

“It’s important – in a well-being sense – to understand that we have to know limitations and be able to not take things personally,” FVMA Wellness and Well-being Committee Chair Dr. Phillip Richmond says. “Sometimes when people say things to us, we don’t have to internalize that and take it as someone being directly upset with us.”

Due to the high demands of those in the veterinary profession, things like wellness and well-being are often put to the wayside when individuals struggle with maintaining a healthy work-life balance, in addition to the stresses that are encountered on a daily basis.

“When we have wellness and well-being in conjunction with this career, it makes us love being a veterinarian again,” Dr. Richmond says. “I still act like a kid. I love what I do, but it took learning about wellness and well-being and putting those things into practice to get to that point.”

Another important thing to take into account is how much the veterinary profession has changed over time. The shift in focus on the type of medicine that is now predominantly practiced has also influenced the state of mental health within the profession.

“The dynamic of veterinary medicine has changed to where there’s a much larger focus on companion animal medicine versus food animal medicine,” Dr. Richmond says. “When we deal with farmers, dairy farmers, ranchers and professionals in the food animal industry, they are looking at the livestock versus a family who has a companion animal — how they perceive that animal is different. There’s more of a human-animal bond with the family pet than there is with beef cattle.”

But one of the most important changes has been the fact that more individuals are starting to normalize having discussions about mental health and working toward eliminating any stigma that may be associated with the issue. Through the use of research and open discussions on a national level at many conferences and meetings, it has helped allow for veterinary students and practicing veterinarians, alike, to be more open about their experiences.

“I think it’s really excellent that we are starting to look into this in a scientific way,” says Dr. Cherie Buisson, who is a member of the FVMA Wellness and Well-being Committee. “We are applying our scientific minds to this problem, and we’re starting to try to figure out what causes this, where we can go from here and what to do.”

24 The Practitioner Issue 1 • 2019

Dr. Buisson, who is a veterinarian in Largo, Florida, owns a mobile end-of-life care practice called Helping Hands Pet Hospice. She also runs a website called “A Happy Vet,” which is dedicated to wellness in the veterinary profession. She says that a big part of addressing this growing issue is by looking at the root of the cause – the contributing factors, including the personalities of those who enter the profession – that attribute to the levels of well-being in the profession.

Contributing Factors to Veterinary Well-being

In recent research regarding veterinary wellness and well-being, there has been a focus on identifying key contributing factors to this problem. Like many careers, components like stress, finances and hours worked are taken into consideration, yet the veterinary profession has many unique factors to it that contribute to the issue of mental health.

With the unique factors of veterinary medicine and patient care where the patient is having their decisions made for them, and how often care plans may be unattainable by clients for a variety of reasons, veterinarians are more often than wanted put into situations of ethical distress. Many veterinarians have expressed how they can be sometimes villainized as people who don’t care because there is a treatment that can be done, yet the client can’t afford it. The blame is then shifted toward the veterinarian as not trying their hardest.

“When you throw emotional clients that are lashing out in anger or pets that are lashing out in fear on top of that, it just doubles and triples the level of anxiety that you experience trying to just figure out how to be a good veterinarian,” explains Dr. Buisson.

very high achievers and tend to be perfectionistic," says Dr. Christy Monaghan, a licensed psychologist working with UF CVM's Student Counseling and Psychological Services Department within the Office of Academic and Student Affairs.

"Those qualities can be viewed as very positive, and they often enable individuals to get into these training programs and to be quite successful. However, it [perfectionism] becomes problematic when the individual holds that as a very rigid selfimposed standard, that ‘I have to be perfect all of the time and when I’m not I am therefore inadequate.’”

There is Hope...

Together Finding Strength to Overcome

Other contributing factors include financial distress (debt owed), social support, sleep deprivation, and the lack of engaging in self-care or self-compassion. Among these factors are three pivotal areas that are often present but not addressed by veterinary students and practicing veterinarians.

Personality Factors

As noted in the Merck Animal Health Veterinary Wellness Study (February 2018), there are many personality traits that contribute to the state of mental health in the veterinary profession. Schools select veterinary students that tend to be very driven, intelligent perfectionist types — but they often don’t always have the resilience needed or the mental coping abilities to deal with failure, which is inevitable once you begin practicing in the field.

“The nature of veterinary medical training and practice can be inherently stressful. In addition, this is further exacerbated by certain personality factors that are characteristic of individuals who go into veterinary medicine. Overall, they are predominantly WWW.FAEP.NET |

She adds that oftentimes individuals struggle with “feeling an overwhelming need to attempt to present this façade of being perfect – and being invulnerable to even typical human frailties,” which is where a substantial percentage of the resulting emotional and psychological distress originates. Dr. Monaghan emphasizes how learning and maintaining healthy coping skills and stress management practices can be effective in helping these individuals deal with inevitable life stressors.

“There are circumstances in veterinary practice where we are not able to provide the desired outcome for the patient, whether due to factors related to the client – such as finances – or to the patient’s medical status, that in it of themselves puts one at a vulnerability for moral distress in terms of not always being able to achieve the outcome you desire,” says Dr. Monaghan.

Imposter Syndrome

Imposter syndrome is a phenomenon that many students going FLORIDAAEP |

@FLORIDA_VMA | The Practitioner 25

through school experience, and it is highly prevalent within the veterinary student population. Imposter syndrome is when an individual often exhibits a pattern of doubts regarding their accomplishments and achievements, fearing they will be exposed as “fake” or a “fraud.” Due to this, this phenomenon is often accompanied by mental health issues, including anxiety, stress or depression. And while it is very prevalent in the academic world, it is also persistent in the medical field among recent graduates who are just beginning their careers.

“I spent the first eight years in practice just feeling like I was letting every one down, and that was just a combination of anxiety and imposter syndrome,” Dr. Buisson says.

A lot of the talks and educational videos that Dr. Buisson has on her website address imposter syndrome, where it often stems from veterinarians’ inabilities to set boundaries and say “no.”

She also says people find comfort in knowing that people from all walks of the veterinary profession attend her talks because many of them just want to know how to make that feeling better or diminish. While as hard as it may be, learning how to not say “yes” to everything helps maintain a healthy work schedule and allows veterinarians to not put patients at risk because they’re trying to see too many and handle too much at once. She also insists that the concept of being worthy and being OK with being unsure about yourself needs to be normalized with individuals when they’re children so that it doesn’t develop into issues later in life when they’re adults and working in their career.

“It was most stressful for me was when I was brand new,” Dr. Buisson explains “I had extreme levels of anxiety when I first got out of school because I felt like I didn’t know anything — and that’s common. You have a foundation but you don’t have a lot of clinical, basic practical experience, so that’s something you kind of learn as you go.”

Compassion Fatigue

Another often-cited component that contributes to the state of mental health in veterinary medicine is what is known as compassion fatigue. It is when an individual experiences the emotional residue or strain of being exposed to those suffering or the consequences of a traumatic event(s). It can occur from just one incident an individual experiences or over a period of time. It differs slightly than burnout, but the two can exist and be present together. Dr. Dani McVety, who is a member of the FVMA Wellness and Well-being Committee and a nationally recognized speaker on the topic of compassion fatigue, explains that veterinarians often end up feeling drained by the people and expectations that they have externally placed on themselves instead of just living by their internal expectations and not apologizing for them.

"We want to do everything right and perfect – the perfect wife, the perfect mother, the perfect business owner, or the perfect employee or the perfect manager,” Dr. McVety says. “We forget that there’s this balance that has to happen, and when we are imbalanced that does not mean compassion fatigue. It just means we need to add something else and reprioritize and live by our priorities and stop apologizing to others who think that our priorities should be different.”

Compassion fatigue symptoms can include loss of self-worth, isolation, loss of morale, an increase in emotional intensity and even sometimes a feeling of existential despair due to a loss of hope. In order to create awareness about this issue so that we do not fall victim to compassion fatigue, it is important to ask ourselves: What types of incidents increase your stress level?

What other issues or contributing factors negatively impact your workday? By asking these types of questions, it helps lower the risk of experiencing compassion fatigue. Dr. McVety also says that having an open, honest and clear relationship with your clients about your medical abilities and their general expectations about medicine can help decrease the risk of compassion fatigue.

There are many resources and outlets to deal with compassion fatigue and other issues of mental health too, including attending compassion fatigue support groups or talking with a life coach on a routine basis.

“When you demystify the struggle like that, knowing that there’s other people out there that are going through it, I think that just adds so much to our lives,” Dr. McVety says. “None of us should be afraid to ask for help or admit that we’ve received help.”

Moving Forward: Helpful Resources & Initiatives

One thing can be certain, which Drs. Buisson, McVety, Monaghan and Richmond all agreed on: This is an issue that many are dealing with, so no one struggling with mental wellness or well-being should feel like they’re alone. There are many of individuals who have gone through this and have found ways to be happy again after seeking mental health treatment or recovery. In recent years, there have been more open discussions about mental health, the stigma surrounding it and encouraging individuals to not be afraid to seek help if they’re suffering. The amount of resources, initiatives and mental health care options has also increased, including efforts by organizations to make those aware of the resources out there.

Veterinary schools are starting to implement wellness activities and check-ins with their students into their programs and extracurricular activities. They’re also establishing their own counselling programs to provide students with professionals who can specifically speak to the issues they’re facing. Organizations across the entire spectrum of medicine, including veterinary medicine, are starting to provide services and resources to help facilitate those in both the academic arena and those working in the profession. There’s a renewed focus on self-care, stress management, communication, work-life balance, addressing compassion fatigue and learning how to maintain positive relationships. It is also important to acknowledge there are instances of substance abuse, so trying to find an avenue to address those in a helpful and clinical way, as opposed to a punitive way, is also important.

The AVMA has been one of the key organizations in the forefront of bringing awareness to the issue of mental health in veterinary medicine. They have an entire section of their website dedicated to veterinary well-being, including a self-assessment, well-being programs and a list of resources on where to get help.

26 The Practitioner Issue 1 • 2019

The FVMA has also begun to address and bring awareness to this issue in Florida. The FVMA is working to compile a list of statewide mental health professionals who are familiar with issues of mental health in the veterinary profession, including medical professional burnout and compassion fatigue, and that list will be made available to FVMA members. The FVMA website will also have informative articles along with links to resources regarding mental health, wellness and well-being. Future FVMA conference, including the upcoming 90th FVMA Annual Conference, will also feature wellness tracks with nationally recognized speakers presenting on topics regarding mental health.

"Take advantage of the resources that are out there,” says Dr. Richmond. “This is a growing area that is getting a lot of needed attention. My hope is 10 years from now, students that are graduating are going to know all these things and have the tools before they graduate to hopefully address these issues and enjoy being a veterinarian.”

If you or someone you know is suicidal or in emotional distress, contact the National Suicide Prevention Lifeline at 1-800-2738255 (TALK). Trained crisis workers are available to talk 24 hours a day, 7 days a week. Your confidential and toll-free call goes to the nearest crisis center in the Lifeline national network.

The Merck Wellness Study (February 2018) and recent CDC study done in conjunction with the AVMA (January 2019) provided meaningful data regarding mental health, wellness and well-being within the veterinary profession.

MERCK WELLNESS STUDY IMPORTANT RESULTS More psychological distress found in younger veterinarians O NL

Veterinarians experience slightly lower levels of well-being than the general population.

REPORTED DISTRESS

8.7%

2.8%

O NL

4

es 55-6 Ag

4

es 18-3 Ag

About 1 in 20 veterinarians suffers

Y

50% Y

41%

of those reporting actually receives treatment of medication for any mental health conditions recommend a career in veterinary medicine

Serious psychological distress increased with number of hours worked, especially those working in the evening hours

from serious psychological distress.

Icon graphics from thenounproject.com

CDC AND AVMA SUICIDE STUDY IMPORTANT RESULTS Veterinarians had a higher proportionate mortality ratio (PMR) for suicide, compared with the general US population.

MOST COMMON METHODS OF SUICIDE

Firearms 45%

Male Veterianrians:

2.1 times

(51%) died from firearm wounds

Female Veterianrians:

3.5 times

(64%) died from pharmaceutical poisonings

Pharmaceuticals 39%

154 of 398 (39%) deaths by suicide over the 36-year study period were the result from pharmaceutical poisoning

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2.5 times that for individuals among the general US population who died by suicide in 2016

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