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The Latest on Equine Health

A look at some of the Kester News Hour selections presented during the 61st American Association of Equine Practitioners annual convention.

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With the slew of studies published in 2015 in addition to conferences, wet labs and other CE opportunities, staying abreast the latest and greatest in equine practice poses time-management challenges galore.

Rather than trying to invent your own DeLorean to travel through time to catch up, simply create an account at PROLibraries, an online resource for educational sessions. Organizations like the American Association of Equine Practitioners (AAEP) post sessions, such as the Kester News Hour (KNH), which can be downloaded and viewed at your leisure.

The KNH is an AAEP Annual Convention staple devoted to sharing current news items in one of three categories: medicine, surgery and theriogenology.

According to Carey Ross, Scientific Publications Coordinator at the AAEP, “The KNH creates diversity in our program with an emphasis on providing practical information for members to take home and use every day.”

Here is a smattering of the KHN selections presented during the 61st Annual Convention of the AAEP, held December 5 to 9, 2015 in Las Vegas, Nevada.

Current Equine News in Medicine

Carol Clark, DVM, Dipl. ACVIM, an internist at Peterson and Smith Equine Hospital in Ocala, Fla., selected ophthalmology studies to present during her first turn in the spotlight.

The first study, “The fungal plaque form of equine keratomycosis” was published in volume 3 of the 2015 edition of Veterinary Medicine and Animal Sciences. The study authors looked at 22 cases of keratomycosis. Of those, 100 percent were successfully diagnosed via cytology, whereas only 60 percent of fungal cultures were positive. Some cases also had a concurrent bacterial infection.

In terms of treatment, 91 percent received at least one antifungal and antibiotic and all horses were treated for secondary uveitis. A keratectomy (i.e., trimming the plaque) was performed in 91 percent of cases; most were done standing. Treatment was long, ≥6.5 weeks, with a favorable outcome (73 percent of treated eyes remained visual).

Key points for practitioners:

  • Use cytology to achieve a diagnosis rather than simply looking and assuming a fungus is involved;
  • Keratectomy promotes vascularization and epithelial cell regrowth;
  • A scar will likely form but is not usually concerning, and;
  • There is a good prognosis for vision overall, but rupture is possible.

The next study, “Clinical, histopathological and immunohistochemical characterization of a novel equine ocular disorder: heterochromic iridocyclitis with secondary keratitis in adult horses” was published in the November edition of Veterinary Ophthalmology. This condition is characterized by ocular inflammatory resulting in anterior uveitis, corneal endothelial inflammation, iris pigment dispersion, and retrocorneal fibrous membrane formation. According to Clark, this is not a good disease to have compared with fungal keratomycosis.

Key points for practitioners:

  • Even in the face of optimal management, long-term treatment is necessary and the outcome is typically poor. These cases don’t reach remission like horses with equine recurrent uveitis.

The Latest on Equine Reproduction

Terry Blanchard, DVM, MS, Dipl. ACT, Texas A&M University, returned in 2015 to present several articles in the field of theriogenology. One of the most practical and interesting studies I found was, “Does Clinical Treatment with Phenylbutazone and Meloxicam in the Pre-ovulatory Period Influence the Ovulation Rate in Mares?” from the October 2015 edition of Reproduction in Domestic Animals.

Included mares were administered either phenylbutazone or meloxicam at therapeutic doses once daily (e.g., for analgesia associated with laminitis, lameness). Deslorin was administered to induce ovulation when mares were in estrus, had a 32 mm follicle, and moderate uterine edema. All controls (i.e., administered only desolorin, not an NSAID) ovulated within 36 to 48 hours, whereas most mares receiving phenylbutazone or meloxicam did not ovulate. Instead, they developed prominent hemorrhagic anovulatory follicles.

Key points for practitioners:

  • Administration of NSAIDs may lead to hemorrhagic anovulatory follicles;
  • Timing of NSAID administration might impact these findings. For example, would it possible or beneficial to stop administering NSAIDs to broodmares with chronic lameness during estrus?

What’s New in Equine Surgery

Liz Santschi, DVM, Dipl. ACVS, Kansas State University’s College of Veterinary Medicine shared these studies in her inaugural session:

1. “Cryptorchidectomy in equids: 604 cases (1977-2010),” published in the April 1, 2015 edition of Journal of the American Veterinary Medical Association. This study described the surgical management of 604 horses undergoing uni- or bilateral cryptorchidectomy. Overall, 60 percent of retained testicles were abdominal. Specific to unilateral cryptorchids, retained testicles on the left were mostly located in the abdomen but retained testicles on the right were usually inguinal. Major complications (diarrhea, respiratory infections) occurred in 18 horses (3 percent), predominantly in horses with abdominal testicles. The mortality rate was only 0.5%. Santschi also relayed that 54 horses (60 percent) had been hemicastrated prior to referral, and 16 (18 percent) were purchased as geldings, inducing the use of a face-slapping emoji.

Key points for practitioners:

  • Major complications are uncommon and mortality is rare, and;
  • If you have a horse with a unilateral cryptorchid on the right there is a decent chance it is in the inguinal canal. If you are comfortable with the surgical technique attempting to remove the retained testicle is a reasonable option. If the retained testicle is on the left, it is likely abdominal and the horse should be referred.

2. “Retrospective analysis of factors associated with outcome of proximal interphalangeal joint arthrodesis in 82 horses including Warmblood and Thoroughbred sport horses and Quarter Horses (1992-2014)” was published in the August 2015 edition of Equine Veterinary Journal. The study authors reported outcomes associated with arthrodesis of the proximal interphalangeal joint (PIP, pastern joint) in horses competing in several disciplines. Indications for arthrodesis included subluxation (dorsal or palmar/plantar), osteoarthritis (OA), and uniaxial plantar eminence fracture. Postsurgically, 45 percent were sound for performance, 37 percent were sound for “use” (broodstock or light riding), 13 percent were lame, and 5 percent were euthanized.

Horses with OA were less likely to be sound (72 percent) compared to horses that underwent arthrodesis for other reasons (94 percent), presumably due to the periarticular reaction in OA horses. Considering the 61 high performance horses (dressage, showing, cutting, reigning, cow horse, roping, show jumpers, hunting, eventers), the success rate was 73% when performed in a hind limb but only 25 percent when performed in a forelimb (a highly significant difference).

Key point for practitioners:

  • Pastern arthrodesis can result in a favorable outcome but high-performance horses with a forelimb arthrodesis have a poor outcome and clients should be made aware of this before electing to proceed with the procedure.

3. Sanchez’s pièce de résistance was, “Prospective study of the primary evaluation of 1016 horses with clinical signs of abdominal pain by veterinary practitioners, and the differentiation of critical and non-critical cases” published in the October 2015 edition of Acta Veterinaria Scandinavica. This prospective study identified features of horses with colic to help practitioners identify critical versus noncritical cases. In total, 167 European primary practitioners were surveyed. Overall, 76.4 percent of cases were deemed not critical (i.e., responded positively to just medical management), leaving 23.6 percent requiring intensive treatment (including euthanasia/surgery). Of those, 12 cases died and 136 were euthanized at first evaluation suggesting that owners may not recognize early signs of colic. No definitive diagnosis was achieved in the majority of cases, leaving the remaining horses diagnosed with simple impaction/displacement, (15 percent), surgical/strangulating lesion (17.5 percent) or miscellaneous causes (10 percent).

Key points for practitioners:

  • Not all clients are familiar with the signs of colic or call their veterinarians soon enough, and;
  • Pain scores (evidence by kicking, pawing, sweating), cardiovascular changes (elevated heart rates, CRT >2 sec, weak pulse character), and lack of gut sounds are the biggest determinates of critical colic at first evaluation.

For more practical tips and techniques to help your practice grow and stay abreast the latest developments in equine practice, watch the KNH in its entirety online and peruse the AAEP Convention Wrap-Up available as a free downloadable report by The Horse magazine (TheHorse.com), an AAEP Media Partner.  

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