The Modern Equine Vet February 2016 by The Modern Equine Vet

The Modern

Equine Vet www.modernequinevet.com

Vol 6 Issue 2 2016

BEVA Congress:

Kickstart wound healing

Recommendation helps find early PPID Taking a good skin sample for the lab Technician Update: Successful management of pleural pneumonia

Table of Contents

Cover story:

Kick start wounds

4 to aid healing

Cover photo courtesy of R. Jim Schumacher

Endocrinology

Test recommendation helps find early PPID ...............................................................10 Dermatology

Skin sampling: Prep it right for the lab..........................................................................12 technician update

Successful management of pleural pneumonia........................................................14 News

Happy or Angry? Your Horse Knows...............................................3 FDA Approves Dewormer for Use in Broodmares.................18 qPCR confirms EHV-5 in horses with respiratory distress..............................................................................19

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news notes

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Happy or Angry? Your Horse Knows Horses appear to be able to distinguish between angry and happy human facial expressions, according to a recent study. Psychologists studied how 28 horses reacted to seeing photographs of positive versus negative human facial expressions. The horses were recruited from five riding or livery stables in Sussex and Surrey, UK, between April 2014 and February 2015. They were shown happy and angry photographs of two unfamiliar male faces. The experimental tests examined the horses' spontaneous reactions to the photos, and the experimenters were blinded to which photographs they were displaying to avoid influencing the horses. When viewing angry faces, horses looked more with their left eye, a behavior associated with perceiving negative stimuli. Their heart rate also increased more quickly and they showed more stressrelated behaviors. The researchers concluded that this response indicated that the horses had a functionally relevant understanding of the angry faces they were seeing. “What's interesting about this research is that it shows that horses have the ability to read emotions across the species barrier. We have known for a long time that horses are a socially sophisticated species but this is the first time we have seen that they can distinguish between positive and negative human facial expressions,” said Amy Smith, a doctoral student in the Mammal Vocal Communication and Cognition Research Group at the University of Sussex who co-led the research. “The reaction to the angry facial expressions was particularly clear — there was a quicker increase in their heart rate, and the horses moved their heads to look at the angry faces with their left eye,” said Ms. Smith Research shows that many species view negative events with their left eye because the right brain hemisphere processes threatening stimuli and information from the left eye is processed in the right hemisphere. A tendency for viewing negative human facial expressions with the left eye specifically has also been documented in dogs. MeV

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For more information: Smith AV, Proops L, Grounds K, et al. Functionally relevant responses to human facial expressions of emotion in the domestic horse (Equus caballus). Biology Letters, 2016 DOI: 10.1098/rsbl.2015.0907

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cover story

Kick Start Wounds

to Aid Healing Consider the stage of the wounds and what is preventing healing B y

M a r i e

R o s e n t h a l ,

When evaluating a wound,

Images courtesy of R. Jim Schumacher

consider the stage the wound is in — inflammatory, debridement, repair or maturation — and how a veterinarian can kick start it into the next phase before beginning treatment, suggested a panel of experts at the British Equine Veterinary Association (BEVA) Congress. “Wound healing doesn’t move steadily from one phase to the next, and there are often overlapping phases. Think about what the impediments are to moving that wound to the next stage,” suggested Patrick Pollock, PhD, se-

Top: Four days after skin graft. Bottom left: Recovering skin for graft; bottom right: applying a split-thickness, meshed sheet graft.

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M S

nior veterinary clinician Equine Surgery of the Weiper’s Centre Equine Hospital, School of Veterinary Medicine at the University of Glasgow. Impediments, such as infection, hypergranulation and repeated trauma, should be managed before the wound can progress to the next healing stage. “I think as a profession, we don’t do wounds very well. We tend to think about what we can buy to put on the wound or what dressings we have in our cupboard instead of thinking two basic questions: What stage is the wound in and what are the things

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Images courtesy of Avalon Medical

cover story

An equine wound before and after the application of RediHeal, which provides a healing scaffold for the wound.

that are stopping the wound from healing,” he said. Many wounds need to be irrigated and debrided, and most veterinarians turn to a “fancy piece of equipment” to accomplish this — a hose. Using a hose is somewhat controversial, because some experts recommend sterile isotonic saline solution for lavaging and debriding the wound, but the panel seemed in agreement that a hose can be a useful and inexpensive method for wound cleaning. “It seems reasonable to accomplish what needs to be done cheaply rather than going to sterile saline physiological solutions,” said Debra Archer, BVMS, PhD, CertES(Soft Tissue), DECVS, MRCVS, professor and head of Equine Surgery at the University of Liverpool. Dr. Pollock said that the large quantities of sterile fluids that are needed to manage a large wound might not be practical in the field. “I think the reality is that we live in the real world, and people keep horses in places where getting a lot 6

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of sterile solution is difficult,” he said. “Tap water is certainly clean enough to put onto a wound … the necrotic debris and the contamination that you remove is far more detrimental to the wound than tap water.” Many topical medications and bandages aid wound healing. In addition to traditional bandages, Dr. Pollock discussed medical grade honey. Manuka medical grade honey not only keeps the wound moist, but also debrides the wound and aids wound healing. “We use quite a lot of honey, and we use medical grade honey,” he said, “because we’ve seen some research that indicated you could get into trouble using household honey [due to contamination],” Dr. Pollock said. “Owners are desperate to go to the store, buy a jar of honey and slap it on the wound with that. It is just that some honeys can be contaminated during processing,” he said. “There is a lot of work to do about honey, but my opinion, based on its use, is that it is ex-

tremely good,” he said. However, because it does debride tissue, honey should not be used during the repair stage when the wound begins to build the matrix for new skin; a veterinarian should recommend something else, such as a hydrogel bandage, which keeps the wound moist without the debriding properties. “If I have granulation tissue, I would not use honey,” Dr. Pollock said, “I would switch to hydrogel bandages.” There was a discussion about packing large wounds, and again there can be disagreement among veterinarians about which wounds should be packed. It can be difficult to pack a chest wound, for instance and keep it airtight, explained Safia Barakzai, BVSc, MSc, Cert ES (Soft Tissue), DESTS, DECVS, MRCVS, a specialist in Equine Surgery and senior lecturer in Equine Surgery at the Royal (Dick) School of Veterinary Studies at the University of Edinburgh. Dr. Pollock suggested using plastic food wrap to help keep the packing materials in and the wound airtight. “Deep puncture wounds will also require systemic antibiotics because of the concern of infection,” Dr. Barakzai added. Keep a close eye on puncture wounds, they warned because they can become contaminated, fill with fluid or lead to secondary conditions, such as pleuritis, depending on where they are located on the body. Some wounds are too large to heal by secondary intention and skin grafting might be necessary, according to Jim Schumacher, DVM, MS, professor in the Department of Large Animal Clinical Sciences, College of Veterinary Medicine, University of Tennessee. There is a case to be made for grafting fresh wounds and a case

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cover story

Progression of wound treated with manual debridement with a hose and a honey dressing, the first to last picture are 4 weeks apart.

to be made for grafting granulating tissue, he said. Grafts take better on fresh wounds, but a lot more skin needs to be harvested to graft a very large fresh wound, he explained. “The advantage to waiting until it begins to granulate is that the wound contracts making it much smaller, so less skin needs to be harvested,” he said.

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Medical doctors tend to prefer grafting human wounds when they are fresh to preserve joint movement, but contraction is good in horses, he said. “Body and neck wounds of horses heal primarily by contraction.” In addition, grafting can kick start a wound that is not progressing to the next stage, he said. “I

think applying a graft to a wound that is not healing very well adds elements to the healing, like cytokines, thus stimulating contraction and epithelialization,” Dr. Schumacher said. In one case he discussed, the horse had been badly burned in a barn fire and required large grafts, even after waiting for the forma-

tion of granulated tissue. Although the horse did well, it developed malignancies seven years later. “An epi-

Bloody Hell A serious side-effect of large equine wounds can be blood loss, according to Mark Senior, BVSc, CertVA, DECVAA, PhD, MRCVS, senior lecturer in equine anesthesia at the University of Liverpool. But it can be difficult to determine how much blood a horse actually lost. “When I talk to vets about how much blood a horse has lost, I think some vets over translate what they know about small animals to horses. “Horses are very good at having a high dynamic response to blood loss. They won’t do the classic tachycardic response to hypovolemia that you see in small animals. That can be very misleading,” he warned. If a horse has suffered considerable blood loss, consider whole blood replacement, Dr. Senior said. Getting a blood donation is relatively easy to do, he explained, using an equine collection kit. Choose the right donor animal, a large horse is better than a smaller one, and certain breeds, such as Quarterhorses and Standardbreds, are less likely to be reactive. A broodmare that has been bred to multiple stallions would be a bad choice because she will likely have antibodies to different blood groups and her blood would be more reactive with the patient’s blood. Horses require cross-matching with minor and major blood groups, but that is not always possible in an emergency in the field. “You can still give blood to horses when you can’t cross-match,” he said, depending on your donor, just start giving it very slowly. There are no guarantees even if there is a cross-match that the patient won’t have a reaction to the donation, he reminded. “However, don’t throw volume at these patients unless you know you can stop the bleeding or know you have no choice,” he added.

thelial scar developed malignant changes,” he said. Dr. Schumacher said he anesthetizes the horse while harvesting a sheet graft because this procedure is very painful. He uses a short-acting anesthetic, obtains the graft, recovers the horse from anesthesia, and applies the graft 24 hours or more later, he said. MeV

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endocrinology

TRH Stimulation Test

identifies early PPID B y

The Equine Endocrinology

Group (EEG) has issued new recommendations that veterinarians conduct the thyrotropin-releasing hormone (TRH) stimulation test to determine the levels of the adrenocorticotropic hormone (ACTH) in horses to better diagnose horses with early signs of pituitary pars intermedia dysfunction (PPID). Recent advancements in testing now enable the TRH stimulation test to more clearly identify the levels of ACTH in horses, according to Nicholas Frank, DVM, PhD, DACVIM, professor and department chair at the Cummings School of Veterinary Medicine at Tufts University, who serves as the coordinator for the five-year-old EEG. The TRH stimulation test should be conducted by veterinarians from mid-November to mid-July, said Dr. Frank. Reference ranges for the TRH stimulation test have not been established from mid-July to midNovember. A baseline blood sample should first be obtained, immediately followed by 1 mL of IV TRH. A second sample is collected exactly 10 minutes later. If the results from the laboratory show the horse’s hormone level at 10 minutes is above 110 pg/mL, then, according to EEG guidelines, the horse is positive for PPID, for-

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T o m

R o s e n t h a l

merly called equine Cushing’s disease. Dr. Frank said the EEG, which is comprised of clinicians and researchers from different countries, is continuing its research to determine the hormone levels indicating PPID at other months of the year to reflect horses’ seasonal endocrine activity. The EEG will be assembling again this summer to develop guidelines for diagnosing insulin dysregulation, a key component of equine metabolic syndrome (EMS) in horses. The TRH stimulation test should not necessarily be administered during a horse’s annual wellness exam, but when the horse shows early signs of early PPID, Dr. Frank said. He noted that the traditional resting ACTH test, while valuable in the diagnosis of moderate or advanced PPID, is not effective in diagnosing early PPID. The TRH stimulation test should replace the resting ACTH Test for early diagnosis of PPID in younger horses. Clinical signs of PPID can be found in horses from 10 years old until the end of a horse’s life. Dr. Frank said veterinarians should keep PPID in the back of their minds when examining a horse. The signs of early PPID are: • Decreased athletic performance,

• Change in attitude/lethargy, • Delayed haircoat shedding, • Regional hypertrichosis, • Change in body conformation, • Regional adiposity and • Laminitis. Steve Grubbs, DVM, PhD, DACVIM equine technical manager for Boehringer Ingelheim Vetmedica Inc. (BIVI), the manufacturer of Prascend, said early signs of PPID may overlap other endocrine diseases, such as EMS. If a horse has delayed or localized shedding, abnormal sweating and/ or laminitis the animal may have PPID. However, because PPID historically has not been considered in the initial list of differential diagnoses, especially in younger horses, experts believe the disease may go undiagnosed and untreated. A change in paradigm is needed, he said. “The mental picture of PPID is that old horse with extremely long hair that just lacked shedding,” Dr. Grubbs said. “When we think about the early subtle signs, we have to rethink this. Look back over the years how we probably missed the subtle signs of PPID because we weren’t considering it, because we just didn’t know.” Dr. Grubbs advised, “Put PPID on your differential list.” To de-

Images courtesy of BIVI.

The top horse has early pituitary pars intermedia dysfunction; the bottom horse has late PPID.

tect the subtle signs of PPID, “you have to actually put your hands on the horse. You can be looking

at the horse for other reasons. If you’re not thinking of early signs of PPID, you would miss it.” The

early clinical signs of PPID should be in the back of a veterinarian’s mind regardless of the age of the horse, he said. If those early clinical signs are spotted, the TRH stimulation test can confirm PPID cases. Earlier diagnosis would result in treatment administered earlier in the disease. Dr. Grubbs said the top signs of early PPID that help him recognize the disease are decreased athletic performance and delayed hair coat shedding, which occurs all over the horse’s body in advanced PPID, but occur in patches and specific areas, such as on the sides of the neck and along the jugular groove in early disease. He acknowledged the difficulty in detecting early PPID because the signs can indicate other conditions. However, the TRH simulation test recommended by the EEG can lead to early detection of PPID. Dr. Frank said that if left untreated, PPID can trigger endocrine laminitis in horses. “If caught early, PPID can be managed,” he said. Dr. Grubbs said a survey by BIVI of 900 horses that were tested for PPID found that the ages of horses that tested positive ranged as young as 5 years old to 30 years old. The highest percentage of horses with PPID was in the 15to 20-year-old range. In the study, the clinical signs with the highest predictability of PPID were abnormal sweating and delayed hair coat shedding. Dr. Frank suggested that veterinarians keep early PPID in the differential for horses showing the symptoms at approximately 10 years old. MeV

For more information: For more information on the EEG, including the Recommendations for the Diagnosis and Treatment of Pituitary Pars Intermedia Dysfunction (PPID) visit http://sites.tufts.edu/equineendogroup/ ModernEquineVet.com | Issue 2/2016

dermatology

Skin Sampling

Prep it right for the lab

Pathologists tend to agree that context is the key to correct interpretation of skin samples.

B y

“As an anatomical pathology

resident, I spent time reading biopsy specimens that had been submitted to UGA’s pathology lab,” said Susan L. White, DVM, DACVIM, professor emeritus of large animal medicine at the University of Georgia. “I have seen a lot of cases where the submitting veterinarian marks an X on a diagram of the animal on the submission sheet and sends it in. That is not helpful when a pathologist is trying to provide useful information.”

Punch Biopsy

Dr. White explained that obtaining a skin biopsy early in the disease progression is advantageous. By the time a veterinarian evaluates a horse with a dermatologic issue, all too often the disease has been present for some time and may have been treated with multiple topical or systemic therapies by the owner.

P a u l

B a s i l i o

Rule No. 1 is to biopsy a primary lesion, but this can be difficult, especially if the owner has already treated the horse. The earlier the biopsy is taken, the more likely a primary lesion will be available for sampling. “Rule No. 1 is to biopsy a primary lesion,” Dr. White said at the 61st AAEP Annual Convention in Las Vegas. “During your physical examination ask the owner to assist

you in identifying primary lesions as biopsies from excoriated or traumatized lesions are not likely to be informative.” In addition, she recommended asking the owner about any anti-inflammatory drugs given to the animal, particularly corticosteroids. A disposable biopsy punch that is 8 mm or larger will give the veterinarian a significantly larger sample when compared with the 6-mm punch that is often used in small animal medicine. The architecture of a skin biopsy specimen is markedly fragile, so Dr. White recommended treating the punch as a circular scalpel. “While applying gentle pressure, turn the biopsy punch in one direction only,” she explained. “You do not want to distort the architecture.” Dr. White recommended obtaining multiple punch biopsies

Often, horses will have disease processes that involve crusts or exfoliative material. These may be important in rendering a diagnosis. “The exfoliative layers of the epidermis or crusts may come off in the process of biopsying the lesion,” Dr. Susan L. White said. “You want to include those in your formalin container so they can be examined as well.” One easy way to take care of these small pieces is to use microscope lens paper that is used for cleaning the objectives on the microscope. The crusts can be folded into a little package, which can then be submersed in formalin until the paper is saturated. That can be submitted to the diagnostic laboratory. 12

Issue 2/2016 | ModernEquineVet.com

Photo courtesy of Dr. Susan White.

Send in the Crusts.

Tools necessary for doing a punch biopsy

when submitting samples. Most diagnostic laboratories will allow examination of up to three punch biopsy specimens for one charge for one submission at one time. Many laboratories do not have a limit for the number of biopsy specimens that can be submitted for a case. “This allows the opportunity to examine several specimens in cases where there is difficulty differentiating a primary lesion from a progression of lesions on different parts of the animal.” The tissue in a skin biopsy specimen will degrade or necrose in short order. In a situation where numerous specimens are required, place each sample in formalin right after it is removed, instead of lining up each sample and placing them in formalin at once, she recommended. Wrapping small specimens in lens paper and labeling it with a pencil before placing it in formalin (pen ink will disappear) can help keep things organized, according to Dr. White.

Make sure you provide some normal skin as well as abnormal skin to give the pathologist a clean normal-toabnormal junction to examine.

“With an incisional biopsy, you can go deeper within the tissue, and include an area that extends into the subcutaneous tissue,” Dr. White said. “In some instances, you can go even deeper into the fascia and muscle planes if you have an eroding or proliferating lesion.” For elliptical biopsy specimens, the strong elastic collagen in equine skin will contract quite a bit when it is placed in formalin, which destroys the delicate architecture of the sample that the pathologist needs to examine. “It’s like writing a message on a piece of tinfoil and then crumpling it up and trying to read it,” Dr. White said. “To avoid this, take the biopsy specimen, place it on heavy paper, cardboard, or even a tongue depressor, and pin it with 25-gauge

Images courtesy of Dr. Susan White.

Incisional biopsy

needles. Wait about 30 seconds for the subcutaneous tissue to adhere to the material you’ve pinned it to, then place the entire piece in a formalin container.” Dr. White recommended obtaining an elliptical specimen that includes some normal skin in addition to the abnormal skin. This can give the pathologist a clean normal-to-abnormal junction to examine. “You want about one-third normal skin to two-thirds abnormal skin

in your incisional biopsy,” she said.

Excisional biopsy

In patients with pustules or small nodules, excisional biopsies may be indicated to remove the lesion as well as examine it. Include a margin of normal skin in the specimen for complete examination purposes. In instances where a neoplastic process is concerned, it is important to identify whether any tumor cells were left behind or if the margins are clean. MeV ModernEquineVet.com | Issue 2/2016

technician update

The successful management of pleural pneumonia By Andrea Whittle A 4-year-old Thoroughbred gelding came into the hospital as an emergency referral. He had won a race two weeks prior and had exercised four days before being referred into the hospital. He was febrile prior to admission with a history of depression. The referring veterinarian had been called out to look at him for three days prior to admission for suspected pneumonia and chose to refer him when evidence of pleural effusion was seen on an ultrasound examination. He was being treated with antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs), IV fluids and periodic distal limb cryotherapy. Upon arrival at the hospital a full physical exam was performed. This horse was reluctant to walk forward when first unloaded. A considerable amount of dark, blood tinged, malodorous nasal discharge was seen from the left nostril. He had an exaggerated respiratory effort with an abdominal component, was nostril flaring with a resting respiratory rate of 40 beats per minute (bpm) and had an occasional, non-productive, cough. His mucous membranes were bright pink with a prolonged capillary refill time of 3 seconds. Thoracic auscultation revealed harsh sounds bilaterally. His GI system was hypomotile although he passed normal manure during the examination. The reluctance to move was not associated with increased digital pulses; his legs were cool to palpate with mild distal limb edema. His heart rate was 64 bpm with bilateral jugular vein fill, a catheter from the referring veterinarian was in place and patent with swelling at the insertion site. His temperature was 101.5° F on admission and he was 1,000 lb on weigh tape. The ultrasound examination of the thoracic region showed significant changes to the lung surface and the presence of pleural fluid. The right side showed areas of consolidated lung with evidence of pleural effusion and diffuse comet tails elsewhere. The left side showed extensive pleural effusion with fluid present 2” above the point of shoulder. After the ultrasound he was sedated (xylazine 80 mg and butorphanol 0.5 cc) for an upper airway evaluation and trans-tracheal wash via a 1.5 meter endoscope. This is accomplished using a triple guarded aspiration catheter (Mila EMAC800) and saline diluent. There was a large yield of thick, almost 14

Issue 2/2016 | ModernEquineVet.com

Blood tinged nasal discharge

black fluid with a foul odor. This was submitted to the laboratory for cytology and culture. A replacement catheter was placed in the RJV; the area was clipped and blocked (Lidocaine) ready for placement of a 14G Arrow over-the-wire catheter, the catheter placed by the referring veterinarian was removed. A complete blood count, creatinine and electrolyte panel were submitted at admission. The white blood cell count was elevated at 15,800 with 78% segmented leukocytes, 20% lymphocytes and 2% bands. The fibrinogen was 800 mg/dL, PCV 39.9% and total protein 6.1 g/dL. His creatinine was 1.0 mg/dL. He was continued on an antibiotic regime of potassium penicillin, gentamicin with metronidazole. Additional treatments included flunixin, pentoxyfylline and omeprazole with probiotics. Firocoxib (0.27 mg/ kg IV load dose then 0.09 mg/kg IV SID) was added for additional NSAID coverage alongside the flunixin. Due to his reluctance to move freely a fentanyl transdermal patch (75 µg patch) was placed over the left cephalic vein and secured with Conform and Elastikon. This was removed after 72 hours and was the only patch used. We placed Soft Ride boots on both front feet as a precautionary measure although he never showed signs of being foot sore and never had elevated digital pulses. The tracheal aspirate grew Escherichia coli and

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Fo r m o re i n f o r m a t ion v ist w w w.a ae vt.or g

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Images courtesy of Andrea Whittle

technician update

The ultrasound examination of the thoracic region showed significant changes to the lung surface and the presence of pleural fluid. The right side (left image) showed areas of consolidated lung with evidence of pleural effusion and diffuse comet tails elsewhere. The left side (right image) showed extensive pleural effusion with fluid present 2” above the point of shoulder.

Streptococcus zooepidemicus; the pleural fluid also grew E. coli. The sensitivity results from these cultures necessitated a change in antibiotics on day 3; the gentamicin was discontinued and replaced with enrofloxacin. The accumulation of pleural fluid was greater on the left side, our next procedure was the placement of an indwelling thoracic drain on the left hand side. An area was identified on ultrasound, clipped and scrubbed in preparation for the placement of a 28 Fr Trocar. The insertion site was blocked, subcutaneous and up to 1” deep with lidocaine prior to a final prep scrub and cut down with a #15 blade. The thoracic drain was placed and secured with a finger trap suture. A sterile pleural fluid sample was taken for cytology and culture before a Heimlich valve was placed and the chest was allowed to freely drain, 4.5 L of fluid were collected. This drain continued to drip and stayed patent for 4 days. The drain was removed on day 4, the site was sutured closed with absorbable suture, padded with gauze and an Elastikon wrap was placed around the abdomen. Ultrasounds were repeated every day and the decision was made on day 2 to place a 28 Fr thoracic drain in the right side of the chest as well. The procedure was undertaken in the same manner as before with additional sedation (total 260 mg xylazine and 0.8 cc butorphanol). The right side drained 8 L of fluid. Ultrasound evaluation of the right side of the chest showed strands of fibrin around the drain insertion site and these eventually clogged the drain on its third day. The 28 Fr drain site was locally blocked (lidocaine), the drain was removed and replaced with a 30Fr thoracic drain; this drain initially gave 5.5 L of fluid then maintained a steady drip for several days. The drain was removed on day 7 when the ultrasound showed only a small pocket of fluid ventral to the drain with significant fibrin strands and a pocket of walled off fluid caudoventrally between ribs 10 and 11. The 16

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left side of the chest showed a fluid pocket ventral to the previous drain site between ICS 5 and 8. One of the biggest nursing challenges with cases of pleural pneumonia is their reluctance to eat and drink. Depression, anorexia, often due to oral medications, and reluctance to move around, usually related to thoracic pain, are all factors to consider. Our patient was initially very sore and unwilling to move around the stall, this gradually resolved with the firocoxib and the fentanyl patch, As soon as he was willing to leave the stall he was taken out for short walks to a grassy area, he wouldn’t always graze but he was much brighter after any time spent outside watching activity around the clinic. Our technicians would groom him outside and let him walk around if he wanted to. Feeding these cases can be difficult, it requires patience and often access to many different feeds to try. The approach that worked well in this case was to offer small amounts of a feed that he liked frequently throughout the day and night on an opposite schedule to all of his oral medications. The technicians would check his vitals Q4hrs and would offer small feeds every time they went into his stall. If there was grain left in the bucket it would be thrown away, the bucket cleaned and small amounts of fresh offered. He started to eat a little better and we were able to schedule feeds to better suit the rest of the barn. Feeding him last out of the horses in his immediate area seemed to increase his appetite. He would eat and drink well immediately after his time outside, the technicians made sure that he had fresh water and a small feed to come in to. We also used a grain-free water flavoring (Horse Quencher) to encourage water intake. He always had access to grass hay and alfalfa offered in the morning and evening. His thoracic drains were monitored for placement and patency Q15 minutes – Q1hr and his legs were

Ultrasound showing the walled-off abscess.

frequently washed to keep them free of drainage to prevent scalding. He had his Soft Rides removed daily to check for rubs and sores; the sole support pads were replaced approximately every 4 days. He was discharged to farm care on day 7 with an IV catheter in place, we planned an antibiotic switch to doxycycline after 7 days. Bloodwork was to be repeated every 7 days. There were several follow up farm calls. A farm call 10 days post discharge resulted in another drain being placed in the right side of the chest; 5 gallons of malodorous fluid were drained from the pleural cavity. This chest tube lasted a couple of days before clogging with fibrin and it was removed by the ambulatory vet. Eighteen days post discharge another thoracic drain was placed into the right side of the chest, caudoventral to the last one, this drain was initially productive and was then used to lavage the walled off cavity that was present with saline and ceftiofur (Excede, Zooitis). The chest tube was removed after 5 days and another follow up ultrasound was performed. The left side of his thorax showed a few comet tails and the right side showing a small accumulation of fluid and consolidated lung. The doxycycline was discontinued, metronidazole was continued and the Flunixin dose was tapered down. An initial dose of ceftiofur was administered. Another farm call was scheduled 10 days later. The physical examination and ultrasound of the chest showed development of a bronchopleural fistula secondary to the infection and a walled off area in the right cranial thorax. A thoracotomy was recommended for the continued treatment of the infection. He had a very poor prognosis to continue as a racehorse at this point despite the aggressive treatment he had received. There was a change in ownership to the ambulatory veterinary who had been monitoring the case since his discharge from the hospital. The goal was to perform the thoracotomy and rehabilitate the horse to have a second career as a show horse for his daughter.

Thoractomy lavage.

Drain and patch. ModernEquineVet.com | Issue 2/2016

technician update

The horse's appetite and attitude remained good, and he gradually regained his weight.

The gelding was shipped back to the hospital. The procedure was performed standing in stocks with detomidine CRI as sedation. A large area of his left thorax was clipped and prepped with drapes placed over his neck and abdomen. The area was extensively blocked with lidocaine. An initial ultrasound guided incision was made by the surgeon. A ~5 inch section of the overlying rib was resected using Gigli wire and wire handles to allow access to the walled off section of lung. A large volume of purulent, malodorous material was removed from the cavity and purulent fluid drained from the walled off abscess. The thoracotomy site was lavaged extensively with warm fluid and subsequently packed with sterile Combine. His thorax was wrapped with brown gauze and bandaged with Elastikon. He was sore walking back to the stall but maintained a fair appetite and attitude overnight. He was maintained on flunixin (500 mg IV BID) for NSAID coverage and chloramphenicol (22.5 g PO QID) for antibiotics. The thoracotomy site was lavaged every day for 11 days with clean lavage tubing and low pressure water. For the first few days the returning fluid was initially thick and white running to clear; by day 11 the fluid return was clear. After each lavage the cavity was packed and re-bandaged, triple antibiotic ointment was placed around the area to prevent scalding. He developed a small capsulated abscess in front of the thoracotomy site tracking under the triceps, this was opened and drained. The thoracotomy site was granulating in well. Our pa-

tient was walked several time a day and care was taken to schedule feedings away from his chloramphenicol treatment times. He was discharged to the owners care. The thoracotomy site continued to heal and granulate well except for a small area caudal to the thoracotomy site, this continued to drain on and off for several months. His appetite and attitude remained good and he gradually put the weight back on that he had lost prior to the thoracotomy being performed. An ultrasound of the remaining draining site was performed 6 months later, the area was small, superficial and walled off with no lung involvement. Since this final examination the gelding has been introduced to an English saddle, was gradually eased into a fitness regime and is now jumping fences and winning ribbons with the owners’ daughter. He spends a lot of time outside and still acts like a racehorse when he is first turned out. MeV

About the author

Andrea Whittle, LVT, graduated with a BS (Hons) in Equine Science while living in England and is studying online for her LVT. Since moving away from England she has worked at Kentucky Equine Research Inc., Waikato Equine Intensive Care Unit in New Zealand and Rood and Riddle Equine Hospital (RREH). She is the Internal Medicine Technician at RREH with special interests in neonatal care and neurology.

FDA approves dewormer for use in broodmares The FDA has granted a new indication for Quest Plus Gel from Zoetis for use in breeding, pregnant and lactating mares. With this latest indication, Quest Plus Gel joins Quest Gel as approved for use in breeding mares. Both meet the individual needs of horses as outlined in the American Association of Equine Practitioners (AAEP) Parasite Control Guidelines. Quest Plus Gel and Quest are the only FDA-approved dewormers on the market that treat and control encysted small strongyles and bots in a single dose. Quest Plus Gel also treats and controls tapeworms, to help meet a horse's individual deworming needs. “The AAEP recommends treatment for tapeworms in late fall after a hard freeze,” said Kenton Morgan, DVM, Equine Technical Services, Zoetis. “For effective treatment, horse own18

Issue 2/2016 | ModernEquineVet.com

ers should consult with their veterinarian and plan to deworm following a hard freeze in order to target tapeworms.” Quest originally launched in 1997 and continues to effectively treat parasites in horses. In 2015, more than 1 million doses of Quest Plus and Quest were sold in the United States, and more than 9 million doses have been sold in the U.S. since 2004. Prior to using a dewormer, a veterinarian should conduct a fecal egg count test to evaluate the horse’s individualized deworming needs. Quest Gel or Quest Plus Gel Gel are contraindicated in foals less than 6 months of age or in sick, debilitated and underweight horses. Do not use in other animal species, as severe adverse reactions, including fatalities in dogs, may result. MeV

news notes

Detection of equine herpes virus-5 (EHV-5) in bronchoalveolar lavage (BAL) samples is consistent finding in horses with suspected equine multinodular pulmonary fibrosis (EMPF), according to a recent study by researchers at the University of California Davis. The diagnosis of EMPF requires histological examination of lung tissue, obtained either by percutaneous lung biopsy or at post mortem examination. “Although histopathological confirmation through a lung biopsy is considered the gold standard for EMPF diagnosis, results of qPCR testing of BALF or a combination of whole blood and nasal secretions should be regarded as clinically useful in support of this diagnosis,” the researchers wrote. “The latter testing may be relevant when dealing with horses in respiratory distress, for which invasive procedures, such as BAL fluid collection or lung biopsies may be detrimental to their health.” Due to the potential risks of lung biopsy, a positive result for EHV-5 in respiratory secretions detected by quantitative polymerase chain reaction (qPCR) is often used to support diagnosis, but its efficacy has never been tested, according to Dr. Nicola Pusterla, PhD, professor of Medicine and Epidemiology at UC Davis College of Veterinary Medicine, and an expert in herpesviruses. Dr. Pusterla and his colleagues looked at respiratory samples from confirmed cases of EMPF and compared them with cases with other lung pathology and normal horses. Seventy adult horses of varying ages and breeds were included in the study. Based on clinical findings, BAL cytology, thoracic imaging and histopathology of lung tissue, the horses were divided into four groups: EMPF, inflammatory airway disease (IAD), non-EMPF interstitial lung disease and the control (horses euthanized for reasons not

Image courtesy of Dr. Pusterla.

qPCR of BAL Confirms EHV-5 in horses with respiratory distress

related to respiratory disease). They took blood, nasal swabs and BAL fluid samples to test for the presence of EHV-5 and the viral load by qPCR. The highest rate of detection of EHV-5 was in the EMPF group in which 91% of blood samples, 82% of nasal swabs and 92% of BAL samples were positive for EHV-5. Viral loads in blood were significantly higher in the EMPF group compared with the other groups. The viral load in nasal secretions was significantly higher in EMPF cases than in the two other lung disease groups. After the EMPF group, the control group had the highest rate of detection in nasal swabs (72%). The high rate of detection in the control group may be reflective of that population or indicate a wider prevalence of latent infection in healthy horses, the researchers said. When both blood and nasal secretions were EHV-5 positive (regardless of the viral load), the sensitivity for that horse having EMPF was 90% and the specificity 89.8%. One horse in the IAD group was positive for EHV-5 BAL fluid with all other positive BAL samples being in the EMPF group. MeV

Gross necropsy showing the consolidated and nodular appearance of the lungs from a horses with EMPF.

For more information: Pusterla N, Magdesian K. G., Mapes S. M. et al. Assessment of quantitative polymerase chain reaction for equine herpesvirus-5 in blood, nasal secretions and bronchoalveolar lavage fluid for the laboratory diagnosis of equine multinodular pulmonary fibrosis. Equine Vet J. 2016 Jan 18 [Epub ahead of print]. http://onlinelibrary.wiley.com/doi/10.1111/evj.12545/abstract ModernEquineVet.com | Issue 2/2016

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