The Modern Equine Vet December 2017 by The Modern Equine Vet

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Equine Vet www.modernequinevet.com

Severe Laminitis

Diagnostic Evaluation And Imaging Producing a Healthy Pasture ... and Horse Castration Complications PRP May Help Corneal Healing News From NEAEP and AAEP Meetings

Vol 7 Issue 12 2017

TABLE OF CONTENTS

DIAGNOSTIC EVALUATION

Tips for Imaging

4 Severe Lameness Cover photo: Shutterstock/varunya

NUTRITION

Producing a Healthy Pasture ..................................................................................................... 9 NEWS

Beta-Amyloid Precursor Protein Promising for Evaluating Equine Grass Sickness Diagnosis.................................... 3 Open Standing Castration May Have High Complication Rate ..............................................................14 Cold Weather Challenges for Horses with OA.................................14 PRP May Help Improve Corneal Healing..........................................15

ADVERTISERS Equinosis........................................................................ 3 Merck Animal Health.................................................. 5

Shanks Veterinary Equipment.................................. 6 Standlee Premium Western Forage......................... 7

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NEWS NOTES

Immunolabeling for β-amyloid precursor protein in rectal biopsy samples is a promising, minimally invasive technique for diagnosing equine grass sickness. Levels of β-amyloid precursor protein are high in cranial cervical ganglia in equine grass sickness cases, so it could improve the accuracy of histological examination of rectal biopsy samples, according to researchers from the University of Edinburgh in Scotland. Biopsies were obtained from 21 grass sickness cases and 23 controls. In all grass sickness cases, the diagnosis was confirmed by necropsy. A grading system was developed that classified the degree of immunolabeling in neurons from grade 1 (sparse labeling of neurons) to grade 3 (diffuse labeling with no unlabeled cytoplasm visible). Horses with grass sickness had significantly lower percentage of grade 0 (normal) neurons and higher percentages of grade 1–3 neurons. Grade-3 neurons were observed in all but one grass sickness case, but

were not seen in any controls. The sensitivity was 95% and the specificity was 100% when the criteria for grass sickness diagnosis were met, and at least one grade-3 neuron was present. The diagnostic criteria and grading system requires more fine-tuning before this technique can be fully applied in clinical cases, the researchers said. MeV

Equine grass sickness

For more information: Jago RC, Scholes S, Mair TS, et al. Histological assessment of β-amyloid precursor protein immunolabelled rectal biopsies aids diagnosis of equine grass sickness. Equine Vet J. 2017 Aug 18 (Epub ahead of print; doi: 10.1111/evj.12710) http://onlinelibrary.wiley.com/doi/10.1111/evj.12710/full

www.equinosis.com

Courtesy of the Equine Veterinary Journal

Beta-Amyloid Precursor Protein Promising for Equine Grass Sick Diagnosis

ORTHOPEDICS

Diagnostic Evaluation and Imaging Severe Laminitis Shutterstock/OLEH SLEPCHENKO

Thanks to the rapidly ex-

panding knowledge associated with laminitis, classification of cases into one of the three main categories is becoming easier. Treatment, however, seems to draw as much controversy as ever, according to James K. Belknap, DVM, DACVS, who spoke at the 63rd AAEP Annual Convention in San Antonio, Texas. To help clinicians sort things out, Dr. Belknap laid out some of his typical treatment processes.

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First steps

blocked, but Dr. Belknap said he’s going to make the horse do the same thing whether it’s blocked or not, so it’s better to cause less duress to the animal. “I’ll perform a transient nerve block using lidocaine in the front feet,” he said. “More commonly, I’m going to target the palmar nerves in the mid cannon region, because it’s easier to do in the standing horse. I do not want to pick up the limbs any more than I have to.”

Following a thorough preliminary physical examination and an accurate history in a markedly painful and lame horse, Dr. Belknap prefers to gather all of the imaging equipment, foot dressings, diagnostic equipment and short-acting nerve blocks in one place. There has been some controversy about blocking the feet and whether the horse could cause more lamellar injury while

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ORTHOPEDICS

After the forelimbs are blocked, Dr. Belknap will walk the horse a few steps to check for hindlimb involvement and place a padded boot on one front foot while he works on the other. He explained that he’s happy to get the horse blocked long enough to obtain imaging and get something on the horse’s feet. He typically has about 30–45 minutes before the horse starts feeling pain again. “I will usually come in laterally to block the mid cannon,” Dr. Belknap said. “In about one-third of cases, the medial nerve will be between the superficial and deep flexor tendons, and not between the deep flexor tendon and suspensory ligament. If you palpate it there, you may have to block it individually on the medial side.”

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After the forelimbs are blocked, Dr. Belknap will walk the horse a few steps to check for hindlimb involvement and place a padded boot on one front foot as he works on the other foot. After an examination of one front foot, he’ll obtain radiographs. If necessary, he’ll remove the shoes as rapidly as possible and provide whatever support is indicated by the radiograph results. The process will be repeated on the other front foot. The horse will be restrained until the block wears off. “The advantages of blocking the feet are that it’s much less distressful to the animal and health professionals, and it’s much easier to position the horse to get decent radiographs,” he said. “We can also do a better job of assessing whether the hindlimbs are involved and get an idea of how much the heart rate comes down.” To avoid further lamellar damage, he will put a pad on the foot that is not being evaluated, he said. “We’ll restrain the horse after radiographs and provide hoof care if the block hasn’t worn off. We just want to make sure we don’t keep any of the feet in the air for very long so there is not excessive weight on the other feet leading to more lamellar damage.”

Imaging

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Dr. Belknap places both of the horse’s feet on a wooden block for radiographs. “Focus your beam about 1 inch above the ground surface,” he said. “In a lateral view, we can certainly diagnose the type of rotation they have and whether symmetric distal displacement (also termed sinking) is occurring. We’ll also get an idea of asymmetrical distal displacement (commonly termed medial sinking) if one palmar process is lower than the other one on the lateral view—this is confirmed on the dorsopalmar view.” It’s important to get an accurate sole thickness (distance from the dorsodistal tip of the distal phalanx to the ground), especially in a horse with a cupped sole. Dr. Belknap suggests placing barium paste on the sole in the toe region in front of the apex of the frog. “You’ll get a more accurate measurement of the sole thickness [with the barium paste],” he explained. “Normally, if you’re just measuring to the ground surface, you’re getting the thickness of the hoof wall. That may not be the same as the sole thickness.”

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ORTHOPEDICS

Main Categories of Laminitis

1 SEPSIS-RELATED Whether a horse has acute metritis, acute abdomen, or gram-negative pleuropneumonia, it’s going to have a fairly typical presentation if it has gone septic, and it’s going to be at risk for sepsis-related laminitis. Classically, these horses have throbbing digital pulses and warm feet. The prodromal/developmental stage (the time between the animal exhibiting signs of sepsis and demonstrating signs of laminitis) is commonly anywhere from 36 hours to several days. “The key thing is that there is a time when the animal is at risk and we can institute prophylactic therapy,” Dr. James K. Belknap said.

A recent study pegged the average sole thickness at 14 mm at the toe.

Founder Distance

“Like most things with laminitis, founder distance is controversial,” Dr. Belknap said. The founder distance, or vertical distance between the coronary band and the proximal limit of the extensor process of the distal phalanx, is not a preferred term by some academics and clinicians, but is commonly used as an indicator of sinking or symmetrical distal displacement of the distal phalanx. It can also increase with rotation. Prior research suggested that if the distance was less than 8 mm, then the horse had a much bet8

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2 SUPPORTING LIMB The prodromal stage of this type can last anywhere from two days to two to three months from the time when the horse develops lameness on the opposite limb to the onset of laminitis. “This is much tougher for veterinarians to know what to do prophylactically,” he said. “You don’t know if the animal is going to develop laminitis, or how long it is going to take.” After the onset of laminitis, however, it’s relatively similar to the other types. The good news is that it's less common. The bad news is that once the horse starts showing signs of laminitis, catastrophic failure happens pretty quickly.

It is important to get baseline radiographs on a horse to compare if the animal does succumb to laminitis at some point. ter prognosis—a distance more than 14 mm was associated with a

3 ENDOCRINOPATHIC These horses tend to not present with the classic signs of a pounding pulse and warm feet. Instead, the process is rather insidious. The horse may present for a routine lameness examination, and the first signs may be from bruising of the sole due to the slow displacement of the distal phalanx. “To me, endocrinopathic laminitis is a rule-out diagnosis of a bilateral forelimb lameness,” Dr. Belknap said.

poorer prognosis. “The problem with that, is that in numerous reports since then, the normal founder distance was reported as anywhere from –2 mm to 14 mm,” Dr. Belknap explained. “It’s difficult to say that if the distance is less than 14 mm on initial radiography then it’s a true displacement.” Therefore, he said, it’s important to get baseline radiographs on a horse. “Whether you’re talking about endocrinopathic laminitis, an atrisk breed, or an animal with a high BCS [body condition score]…it’s great to get a baseline, at least with lateral radiographs,” he said. “You can compare radiographs if the animal does succumb to laminitis at some point.” MeV

Grazing & turnout on breeding farms:

Healthy Pastures Produce Healthy Horses B y

C a r o l j e a n

E l l i s

Well-maintained pastures not only meet and exceed a horse’s protein, vitamin and mineral requirements, they also reduce colic, gastric ulcers, respiratory disease and a host of other disorders. “Forage is the foundation of equine nutrition,” explained Bridgett McIntosh, PhD, at the recent Northeast Association of Equine Practitioners annual symposium in Norfolk, Va. “It isn’t rocket science, but there’s a lot everyone can learn about adopting best management practices in keeping pastures healthy. ” Pasture and grazing management are particularly crucial on breeding farms. “It’s really essential when talking about broodmares—or really any horse—to get owners thinking about why their pastures are so important,” said Dr. McIntosh, who is an equine extension specialist at Virginia Tech’s Middleburg Agricultural and Extension (MARE) Center in Virginia. Overgrazing and manure disposal are two of the most common problems encountered. Although not all variables can be discussed here, other inherent management considerations include: • Forage selection—cool season versus warm season grasses • Planting do’s and don’ts • Grazing parameters, turnout time and stocking rates • Soil health • Nutritional diseases associated with nutrient content in pasture plants Unfortunately, overgrazed pastures often take three-to-five grazing

Courtesy of Robert Drake

NUTRITION

ModernEquineVet.com | Issue 12/2017

NUTRITION

Courtesy of Dr. Bridgett McIntosh

and compacting the soil prevents the plant’s uptake of water, oxygen and nutrients needed for survival. • Overstocking: At least 2 acres of pasture is required per horse to provide adequate forage. There’s no doubt about it, Dr. McIntosh added: Realizing success may seem daunting at times, but the end result is well worth everyone’s time, energy and dedication.

Courtesy of John McCormick

FIGURE 1: Improper manure management can lead to pollution of nearby creeks and escalation of unhealthy pathogens (Escherichia coli), as well as damage to healthy plant nutrients.

FIGURE 2: Tall fescue is a hardy, very nutritious forage grass, although KY-31 endophyte-infected tall fescue can be problematic for pregnant mares.

seasons before they realize any measurable change, Dr. McIntosh noted. “Getting horse owners to follow the best management practices needed to maintain grazing areas, conserve the environment and provide nutrients to their horse herd can be timeconsuming and challenging, but it’s not impossible.” In addition, proper manure management is essential to protect water resources and provide a healthy environment for horses, said Dr. McIntosh, who assists a number of farms through university-based extension programs. “Improper manure storage allows nutrients and pathogens, including Escherichia coli, to run off into the water and degrade water qual10

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ity (Figure 1). Manure should be stored at least 100 feet from water sources, including streams, ponds and wells.” Interestingly, the horse itself can introduce a separate set of problems: • Selective grazing: Horses routinely select the same specific areas to graze within the pasture or paddock, rather than grazing the entire field, and do not graze areas where they defecate when given a choice. • Top grazing with incisors: Grazing down to the base of the plant eliminates the plant’s storage area, which is necessary for regrowth. • Weight of animal: A 1,200-lb animal repeatedly trampling

Where to Begin?

The first question to ask owners, Dr. McIntosh said, is whether the purpose of the pastures is for exercise or for nutrition—that is—how much of the farm’s acreage is devoted to grazing. “Pasture forage is a cost-effective feed source that also provides exercise opportunities that can minimize respiratory problems and lower risk for digestive disorders.” But Dr. McIntosh continued, "A lot depends on total usable acreage. Typically, about 2 acres per horse is needed for grazing, although some farms may need 3 or 4 acres and others might be managed using only 1 acre per horse if best management practices, including rotational grazing and dry lots, are used.” Reducing turnout time (i.e., access to pasture) does not necessarily reduce the amount of pasture needed, however, “We used to think that reducing turnout time automatically reduced the amount of needed acreage,” she said, “but now we know that this is not true. If you reduce a horse’s turnout time and the horse learns that it only will have four hours of turnout, it will adapt by simply spending that full four hours eating.” Fortunately, potential solutions for small acreage farms are in the works. In conjunction with the University of Maryland, the MARE Center has been conducting a study of turf grass varieties

Forage Grasses: The Good, the Bad, the Ugly

There are two types of grasses: cool season and warm season. In the greater Northeast region, cool season grasses predominate. From the mid-Atlantic states and southward, various combinations of cool and warm season grasses are more workable. Crabgrass is a warm season grass that may not be desirable for lawns but is a great nutritional selection for horse pastures. The average grass forage can exceed the nutritional needs—not including, of course, copper, selenium and zinc—of most horses. “However, even when forage meets or exceeds protein, mineral and energy requirements of most horses, that same pasture may fail to meet the needs of mares in later stages of gestation,” Dr. McIntosh said. Fetal uptake of minerals is greatest in the last three months of gestation. The mare will fortify the unborn foal liver with minerals such as copper, zinc and selenium. Mare’s milk is not a good source of these trace minerals; therefore, they must be stored in the foal’s liver prior to birth. Tall fescue is a very useful grass in horse pastures (Figure 2) because it is hard to kill, very nutritious and withstands a lot of wear and tear. But the most common tall fes-

cue variety—Kentucky-31 (KY31)—also is the No. 1 culprit to avoid on breeding farms, as its negative impact on pregnant mares and unborn foals during the last 60 days of gestation can be devastating (see Did You Know …). “We struggle with this dilemma on our farm in northern Virginia,” Dr. McIntosh explained, “as it is right in the heart of what is called the fescue belt.” However, once again, research is coming to the rescue by introducing KY-31 varieties that have a novel endophyte, allowing the plant to maintain its durability and resist drought and overgrazing without worrying about reproductive issues. In addition to tall fescue, cool season grasses used in parts of the Eastern seaboard include orchardgrass and Kentucky bluegrass. “Of course, the health of all grasses relies on pasture maintenance,” Dr. McIntosh emphasized. “Orchardgrass, for example, will not persist and will form ‘clumps’ if overgrazed.” In addition, Dr. McIntosh recommended planting about 20% ladino white clover because it is beneficial to forage grasses, reducing the amount of nitrogen fertilizer needed to keep pastures growing and healthy.

Planting Do’s & Don’ts

The peak growth period for cool season grasses is the spring and autumn months, as they fail to do well in ambient temperatures above 80°. In the transition zone from Pennsylvania and Maryland down through the mid-South, warm season grasses can be planted in late spring and early summer and can be grazed within 60 days. “They grow well when it is about 85° to 90° and dry,” Dr. McIntosh said, “and do not require as much water and moisture as their cool season counterparts.” Cool season forages need to be planted by early fall, she explained. “Once you get to spring, it’s really

Did You Know … A bit of tall fescue history … • Tall fescue is called the Wonder Forage. • It’s a great cool season grass originated in 1943 and found to be widely adaptable to drought. • You can graze the heck out of it. • It’s resistant to pests. • It’s really easy to establish. • It’s harmless to most horses. BUT, it’s not a wonder forage for pregnant mares … • The endophyte fungus that allows tall fescue to be rugged and tough and endure all challenges produces a toxic ergot alkaloid that allows the plant to survive. • But when a pregnant mare in the final 60 days of gestation eats the toxic KY-31 variety, a lot of problems can develop, including: – Dystocia and agalactia – High foal death rate – Weak and poorly muscled foals – Poor milk production – Retained placentas – Abortion • Today, research has introduced safe KY-31 varieties that contain a novel endophyte.

Shutterstock/Volodymyr Nikitenko

for small-acreage farms. “These turf grasses will be a dense vegetative cover that allows horses to graze but also anchors the soil,” Dr. McIntosh explained. As part of the study, they have looked at eight varieties of cool season grasses and six varieties of warm season grasses. The study ended October 2017, and it is hoped that the recommendations will lower the amount of acreage required on small farms while increasing the stocking rates and thereby reducing the number of overgrazed pastures.

too late, so we over-seed cool season forage in August to September, which helps establish the plant and allows sufficient time for the root base to take in nutrients before winter sets in.” Clovers can be established by frost-seeding in the late winter months. The key to establishing pastures is not to graze them too soon. “So, what we really recommend is not using a newly seeded pasture [Figure 3] but instead letting it rest for a year, or at least until the following summer, so the young seedlings have a chance to establish themselves without being subjected to grazing pressure.”

Overgrazing Strategy

At the end of the day, overgrazing is the primary cause of unproductive pastures; maintained pastures should ModernEquineVet.com | Issue 12/2017

Courtesy of Dr. Bridgett McIntosh

NUTRITION

FIGURE 3: Pastures should be well established before being subjected to grazing pressures. The recommendation is to allow seedlings planted in the fall to grow at least until the following summer before a pasture is grazed.

have at least 75% desirable plants. If the pasture contains less than 50% desirable plants, management intervention will be required, including over-seeding, herbicides and fertilizing based on soil testing results. “But if you go out to a farm where there is a lot of bare ground and less than 50% desirable plant species with overgrazed patches of dirt—it will be a complete renovation process,” Dr. McIntosh said, adding that realistically the farm would have little chance of improvement without complete rest and renovation. “That’s why we’re hoping some of the turf grasses being studied at the University of Maryland will eventually come into play.” The concept of safe grazing is called take half, leave half. Monitoring vegetative growth is key. Using tall fescue as an example: • The optimal vegetative height of tall fescue is 6 to 8 inches. • If the height is grazed down by 50% (i.e., take half, leave half), only 2% to 4% of the root growth is affected. • But if the plant is grazed down to 2 inches, root growth is stopped by 78%; and down to an inch—by 100%. • So, grazing close to the base kills the plant. 12

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If owners are concerned about a horse or have limited farm acreage for foraging, it's time to think about hay selection. “To be safe,’ Dr. McIntosh explained, “tall fescue needs at least 3 inches to allow regrowth. Some warm season grasses can be grazed down to 2 inches.” The best solution to overgrazing is introducing a rotational grazing system. This works well on nonbreeding farms, but on breeding farms, it has some drawbacks. Temporary electric fencing is commonly used to divide paddocks for rotational grazing. On a nonbreeding farm, only one strand of electrical tape could temporarily divide a 7-acre grazing system for four adult horses—basically—

FIGURE 4: Rotational grazing, the best solution to overgrazing, relies on temporary fencing. On nonbreeding farms, temporary fencing simply uses a single strand of electrical tape to keep adult horses within designated grazing sections. But this does not work on breeding farms, as a single temporary strand of tape will not confine a foal; rather four strands of tape mounted on more permanent posts are needed to contain foals within each rotational pasture.

there are four lanes, and each lane has a two- to four-week rest period between grazing, depending on the growing season. It’s a bit trickier, however, when foals are turned out with their dams because, in general, foals cannot be contained by a single temporary strand of electrical tape. Rather, about four electrical strands of tape on permanent posts (Figure 4) are needed to contain foals in a similar rotational grazing pasture.

When Hay Is the Answer

If owners are concerned about a horse or have limited farm acreage for foraging, it’s time to think about hay selection, Dr. McIntosh said, adding that “it’s very important to know the mineral and nutrient content of your hay.” • Laboratory testing is the only way to determine the energy and nutrient content of hay. • First-cut hay is typically less digestible and lower in nutrient content. • Alfalfa hay is high in energy and nutrients, making it an ex-

Final Words

When Dr. McIntosh was working toward her PhD, she was curious about a horse’s grazing behavior. “We put pedometers on Thoroughbred mares and found that they graze anywhere from 14 to 16 hours a day,” as averaged across different seasons with full-time turnout, lower grazing times during the hot summer and higher grazing times during the cool fall and winter months. Interestingly, mares in 12- to 15acre pastures during the same 48hour study period moved 10 miles a day. “I found it really surprising that they traveled that much,” she added, “and I really like to think this reflects

Effective Use of Dry Lots Use of a dry lot is one of the best management tools designed to preserve the condition of pastures when a horse should not (eg, because of obesity) or cannot (e.g., because of limited acreage available for grazing) be turned out to pasture. A properly designed dry lot can: • Avert overgrazing of pastures (eg, grass in short supply) • Avoid damage to pastures during extreme wet or dry conditions • Control amount of daily grass consumption, thereby managing obesity Covered round hay feeders in a dry lot help control the amount of feed consumed by overweight horses. In addition, hay feeding in dry lots is an effective alternative to full-time grazing, particularly on small acreage farms.

normal evolution of horses mimicking natural behavior. The more horses are confined to stall feeding, the less opportunity for natural mobility and motility of the gut.” When talking about broodmares, Dr. McIntosh stressed how essential foraging in a well-maintained pasture is to the horse’s health, adding that a sound breed-

Courtesy of Dr. Bridgett McIntosh

cellent choice for broodmares in late gestation and young growing horses. • As discussed, do not feed KY31 tall fescue hay to pregnant mares, especially in the last 60 days of gestation; the novel endophyte variety is safe for all classes of horses, including mares and foals. • Do not feed hay containing Johnsongrass, fall panicum, switchgrass or kleingrass to any class of horses. Dr. McIntosh explained that what is good-quality hay for one horse may not be for another. “If I am feeding a mare in late gestation, the hay I select for her is going to be different than what I select for a fat pony.”

ing program should include conservation practices (e.g., pasture and manure management) that, in turn, provide an ideal environment for raising healthy foals. As owners recognize the significance of land conservation on horse health, the more likely they will adopt best management practices, she predicted. MeV

For more information: Bamka WJ, Justin JR. Establishing and managing horse pastures. New Brunswick, NJ: Rutgers, The State University of New Jersey, Agricultural Extension Station, Cooperative Research; Factsheet FR368; 2003. Ball DM, Hoveland CS, Lacefield GD. Southern Forages. Atlanta, GA: Williams Printing Co; 1997. Cross DL, Redmond LM, Strickland JR. Equine fescue toxicosis: signs and solutions. J Anim Sci. 1995;73(30:)899-908. McIntosh B. Best practices for managing pastures, hay and turnout facilities on a breeding farm. In: Proceedings of the NEAEP: Internal Medicine/ Reproduction. Norfolk, VA: 2017;67-70. Putnam MR, Bransby DI, Schumacher J, et al. Effects of the fungal endophyte Acremonium coenophialum in fescue on pregnant mares and foal viability. Am J Vet Res. 1991;52(12)2071-2074. ModernEquineVet.com | Issue 12/2017

NEWS NOTES

Open Standing Castration May Have a High Complication Rate

Photo courtesy of The Equine Veterinary Journal

Open standing castration may have a far higher complication rate than previously thought. Researchers performed a retrospective, cohort study to investigate the prevalence of postoperative complications following routine open, standing castration in a closed population of Thoroughbreds in Hong Kong.

Open standing castration may have more complications that previously thought.

They analyzed data from 250 horses castrated over a five-year period to determine the prevalence of complications in the 30-day postoperative period. Sixty percent of horses (n=150) experienced complications, which is up to three times higher than previously reported. More than 56% (n = 85) of complications were classified as mild (e.g. seroma formation, mild infection, mild colic); 38% (n = 57) of complications were classified as moderate (e.g. seroma formation requiring digital opening of the wound, funiculitis, loose feces or moderately painful colic); and 5.3% (n = 8) of complications were classified as severe (e.g. pyrexia, excessive and prolonged hemorrhage, peritonitis). There was a significant difference between complication severity and time to return to galloping and racing. Despite variations in technique such as ligating the testicular vessels, performing scrotal ablation etc., postoperative care was reportedly within standard practices and the veterinarians performing the procedures were experienced clinicians. There was also no association between rate of complication and month or season. MeV

For more information: Rosanowski SM, MacEoin F, Graham RJTY, et al. Open standing castration in Thoroughbred racehorses in Hong Kong: Prevalence and severity of complications 30 days post-castration. Equine Vet J. 2017 Oct. 7 (Epub ahead of print). http://onlinelibrary.wiley.com/doi/10.1111/evj.12758/full

Cold Weather Challenges for Horses with Osteoarthritis Plunging temperatures, deep snow and freezing rain— even a change in barometric pressure—may trigger joint discomfort, pain, deformity, loss of motion and decreased function in horses with osteoarthritis. “Our aim is to control the progression of the disease by focusing on alleviating joint pain and inflammation, which allows the horse to maintain or increase mobility,” said Hoyt Cheramie, DVM, MS, DACVS, senior equine professional service veterinarian, Boehringer Ingelheim. He suggested that veterinarians urge owners to continue exercising their horses during winter, which helps the joints to stay supple and moving. “The more horses have a chance to stay fit, the better it is for their overall joint health,” Dr. Cheramie said. “However, it is especially important for OA sufferers to have a warm-up and cool-down regimen before and after work, and that the work is not excessive.” 14

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He recommended slow, easy, stretching movements to help loosen muscles and get the circulation going in stiff joints. He also offered these cold weather management tips: • Be cautious when riding in deep, heavy or wet snow as this may be associated with tendon injuries. • If horses are exercised enough to generate sweat, clip them to help them cool down faster. • Blanket horses that are clipped or don’t have a thick hair coat. • Turn horses out as often as possible if they are not ridden. • Provide ample bedding for warmth and to cushion elbows, hocks and other sensitive areas for stabled horses when lying down. Tell owners to contact you when OA-associated pain and inflammation flares up to discuss a management plan. BI has two products that could help:

Platelet rich plasma (PRP) may be an effective treatment for horses with corneal disease, but more study is needed. Many horses with corneal ulcer disease require surgical intervention. Based on its anticollagenolytic properties, veterinarians have been applying serum topically for equine orthopedics. Because the presence of growth factors promote corneal healing, it has also been used in human ophthalmology. However, there have been no reports of the effects of these blood-derived products on horses with corneal disease. In a new in vitro study, researchers aimed to evaluate the potential use of PRP and plasma rich in growth factors (PRGF) for corneal disease in horses. Whole blood was collected from 35 healthy horses and processed to yield serum—PRGF (using the Endoret PRGF system) and PRP (using the E-PET system). The corneas from six horses deemed to have no corneal abnormalities were removed within one hour of euthanasia and the corneal limbal and stromal cells collected, which were treated with a medium containing 20% of one of the three blood-derived products. Cell proliferation and migration were then compared among treatment groups in both single cell and co-culture systems. After 48 hours, cell proliferation was seen to increase in the PRP group, remain relatively constant in the PRGF group and decrease upon serum treatment. However, overall, there was no significant difference between the groups in relation to cell proliferation. Cell migration was

Photo courtesy of The Equine Veterinary Journal

PRP May Help Corneal Healing

Corneal ulcer disease

significantly higher in the serum and PRP groups, and closure of a cell-free area was significantly faster in the PRP group. “The results demonstrate beneficial effects of PRP on proliferation as well as migration capacity of equine corneal cells in vitro. In vivo studies are warranted to determine further beneficial effects of PRP in horses with corneal ulcers,” the researchers wrote. MeV

For more information: Rushton JO, Kammergruber E, Tichy A. et al. Effects of three blood derived products on equine corneal cells, an in vitro study. Equine Vet J. 2017 Nov. 3 (Epub ahead of print). http://onlinelibrary.wiley.com/doi/10.1111/evj.12770/full

Photo courtesy of Boehringer Ingelheim

firocoxib (Equioxx), and 1% diclofenac sodium (Surpass). Firocoxib inhibits the inflammatory enzymes (cyclooxygenase-2), while sparing the enzyme (cyclooxygenase-1) that safeguards a number of normal body functions, including stomach protection. Diclofenac is the only FDA-approved topical application in horses to control pain and inflammation associated with OA in hock, knee, fetlock and pastern joints. *Merial became part of the BI group in 2017.

For more information: Schlueter AE, Orth MW. Equine osteoarthritis: a brief review of the disease and its causes. Equine Comp Exerc Physiol. 2004;1(4):221-231. University of Minnesota, Extension, Equine Winter Care. Available at: http://www.extension.umn.edu/agriculture/horse/care/equine-wintercare/ Accessed Dec. 26, 2017. Caldwell FJ, Mueller PO, Lynn RC, et al. Effect of topical application of diclofenac liposomal suspension on experimentally induced subcutaneous inflammation in horses. Am J Vet Res. 2004;65(3):271–276. ModernEquineVet.com | Issue 12/2017

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