The 2001 annual convention of the American Association of Equine Practitioners served up a banquet of information for veterinarians and horse owners. One full day was devoted to owner education, featuring veterinarians speaking on a variety of topics. Veterinarians enjoyed one day of committees and forums on various topics, followed by three full days of lectures. There were also two days of hands-on wet labs. Some days the sessions started over breakfast at 6 a.m., and some days offered luncheon topics. The installation of new officers and recognition of award winners were done at a special luncheon. There also was a trade show for veterinarians to shop for the latest in equipment and products.

Following are short synopses of some of the presentations covered by The Horse staff during the AAEP Convention. Full texts of these articles can be found online at with the designated article quickfind numbers given with each topic. Subscribers will receive a supplement with their February issue of The Horse that features extensive coverage of the AAEP convention, with our staff selecting topics of interest to horse owners and translating them from "vet speak" into layman's language. You can also see additional topics at 

Horseman's Day

More than 350 people came out to hear six speakers and in almost every case were still asking questions when moderator Eleanor Green, DVM, Dipl. ACVIM, Dipl. ABVP, Dean of the University of Florida's Veterinary School, was forced to halt the discussion to introduce the next speaker. The speakers agreed to stay at the sessions so they could field questions during breaks.

Horseman's Day was held for the first time last year during the AAEP convention in San Antonio, Texas. Many attendees at this year's conference in San Diego, Calif., were from southern California, but they also came from places like Ohio, Colorado, Pennsylvania, and Canada. Horseman's Day also will be part of the convention next year in Orlando, Fla.

The speakers were Brett Scott, PhD, professor and extension horse specialist at Texas A&M University, on nutrition; Jack Snyder, DVM, PhD, chief of equine surgery and lameness at the University of California, Davis, on colic; K. Gary Magdesian, DVM, the University of California, Davis, on emergency first aid; Bill Moyer, DVM, head of the Department of Large Animal Medicine and Surgery at Texas A&M University, on laminitis; G.F. Anderson, DVM, of Equine Veterinary Associates of Broken Arrow, Okla., on trailer loading; and Barrie Grant, DVM, MS, of San Luis Rey Equine Hos pital, Bonsall, Calif., on lameness vs. neurologic problems.

At the conclusion of his talk, Grant showed a film of perhaps his most famous patient--Thoroughbred Triple Crown winner Seattle Slew, who is now in his mid-20s. The horse was suffering from spinal cord compression that made it impossible for him to cover mares. Grant and members of his staff traveled to Kentucky where Grant successfully performed surgery that allowed Seattle Slew to return to the breeding barn.

For more on Horseman's Day, see article #3161.

Cushing's Disease

There have been advancements in the diagnosis and treatment of Cushing's disease, but previously there were no studies comparing the two most used medications--pergolide and cyproheptadine. Harold Schott II, DVM, PhD, presented "The Michigan Cushing's Project," involving a study from 1997 to 1999 at Michigan State University. Researchers and Michigan veterinarians followed 77 horses confirmed to have Cushing's disease. The horses were divided into a control (non-treated) group, those treated with pergolide, and those treated with cyproheptadine.

It was found that clinical improvement and a reversal of abnormal endocrine test results were better with pergolide than with cyproheptadine. In fact, treatment with cyproheptadine was found to be of little benefit when responses were compared with those observed in horses not receiving treatment. In addition, it was found that measurement of plasma adrenocorticotropin (ACTH) concentration alone is not a reliable endocrine test for diagnosis of Cushing's disease, since both false positive and false negative results were obtained when compared to a low-dose dexamethasone suppression test (DST) or a thyrotropin-releasing hormone stimulation test.

For more on Cushing's disease, see article #3162.

The Pruritic (Itchy) Horse

We've probably all had, or at least seen, a horse with an itching problem no one could quite figure out. At an AAEP roundtable session, veterinarians discussed how to diagnose and manage these horses to keep them comfortable and unblemished.

"It's very important to use management as well as products," said Susan White, DVM, MS, Dipl. ACVIM, professor at the University of Georgia and moderator of the session. For example, if the horse's worst problem is a sensitivity to insect bites, hang fans in the stall or run-in shed and direct them at all levels of the horse, including the legs and abdomen (this will require multiple fans).

Another option is to find out to which insects a horse might be hypersensitive, then manage him accordingly. For example, if a horse has a problem with dusk or evening-dwelling mosquitoes, then turn him out in the daytime and apply fly repellent when you bring him in at night.

Fly repellent is definitely not a panacea, however; White estimated that 20-30% of the problem horses she sees are allergic to pyrethrins, a common class of insect repellent. Intradermal skin testing is quite useful to identify such sensitivities, she added.

When diagnosing the cause of a horse's incessant itching, it is smart to make sure that a horse is not on steroids or any other medication that might affect his immune system's response to testing. This is usually best done in the fall, or whenever insect activity in the area decreases. Once the cause is diagnosed, then the owner and veterinarian should plan a management program to be in place before the next year's initial onslaught of insects.

There are also dietary causes of persistent itching in horses. According to White, "The main thing is to simplify diets. Today's horse is often not on one supplement, it may be as many as 14. We need to simplify topical products and feed for these horses." White and other attendees had seen horses quit scratching when molasses and sometimes long-stem hay were removed from their diets. Again, testing is needed to determine the cause.

Tips for owners included minimizing topical repellent use where possible, using repellents that are labeled for horses, keeping horses clean without washing them so much that there is over-drying of the skin (which can worsen itching), and minimizing horses' exposure to whatever causes their individual problems.

For more on the pruritic horse, see article #3092.

Review of Probiotics

The definition of probiotics was refined in 1998 to "living microorganisms, which upon ingestion in certain numbers, exert health effects beyond inherent basic nutrition." Probiotics have been increasing in popularity due to their ability to reduce the use of antibiotics, their degree of safety, and an increase in the public's desire for more natural products. Scott Weese, DVM, DVSc, Dipl. ACVIM, of the University of Guelph in Ontario, Canada, presented the history and basic concepts of probiotics for use in human and equine medicine.

In horses, it is thought that probiotics might be most useful in preventing and treating antimicrobial-associated diarrhea, treating various types of acute and chronic diarrhea, preventing nosocomial (acquired in the hospital) diarrhea, and preventing acute infectious (especially rotaviral) diarrhea in foals.

Weese said that certain probiotics might be effective in treating or preventing certain conditions; however, all probiotics will not be effective for all conditions. Knowing the properties of the various products is important when trying to determine their use. Unfortunately, there is little information on efficacy or dosage in the horse. Assumptions cannot be made from human medicine, nor from research done on other species--some of these probiotics will react differently in the horse, and some might not have any effect at all.

Since no studies have shown probiotics to be effective in horses, it is difficult to make specific recommendations. If a probiotic is to be used, Weese recommended that organisms that have been shown to be effective in other species would be preferable, such as Lactobacillus acidophilus, Lactobacillus rhamnosus, and Lactobacillus casei.

Dosing of these organisms is unknown. He recommended that horses should be fed at least 10-100 billion bacteria per day. Research is ongoing to identify specific probiotic strains that possess beneficial properties. Organisms must be able to:

  • Survive transit through the acidic environment of the stomach and resist bile digestion;
  • Adhere to intestinal epithelial cells, colonize the intestinal tract, produce an anti-microbial factor, and be non-pathogenic.

To be considered a viable commercial product, a probiotic should be safe, have no undesirable effects on the host, be robust enough to grow in commercial conditions, and survive processing and storage. More studies are needed to determine the mechanism of action for a probiotic.

"Hopefully, future research studies will provide insight allowing more specific selection of probiotic preparations," said Weese. "In the meantime, an understanding of the general principles of probiotics and of their application in other species can allow the practitioner to make reasonable choices."

For more on probiotics, see article #3166.

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