10/25/2001 11:00PM

Buyers beware of certain larynx conditions

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LEXINGTON, Ky. - Certain abnormalities in sales yearlings' larynxes are more likely to hurt future racing performance, a study in the Journal of the American Veterinary Medical Association says this month. But just as importantly, the study also revealed that other throat characteristics that traditionally have raised red flags actually have little effect on future performance.

The study compared endoscopic exam scores veterinarians gave 427 Keeneland September yearlings with the horses' race records through their 4-year-old season. It found that many epiglottis and soft-palate abnormalities the veterinarians described had little negative effect on the horses' ability to run. But findings of grade 3 or grade 4 abnormalities - considered the most serious - in the larynx did predict poorer racing performance.

A grade 3 score indicates that one of the arytenoid cartilages, the twin cartilage "flappers" in the voice box that close during swallowing and open during breathing, does not open fully or does not stay open; a grade 4 score, considered a serious fault, means that one side is nearly paralyzed. Horses with grade 1 and 2 scores, which indicate little to no abnormality in the cartilages' function, generally performed better than horses with worse scores.

The study, authored by veterinarians at Michigan State University and the Lexington veterinary firm Equine Medical Associates, sheds light on the ability of a common pre-purchase exam to predict future breathing problems. That's important for virtually all players in the sale process: buyers seeking assurance that their horses will at least be able to run, the veterinarians charged with making that call, and the sellers, whose livelihoods depend on the sales and whose most popular yearlings sometimes undergo 15-20 endoscopic exams before auction.

"These findings strongly confirm that horses should be examined endoscopically prior to purchase to evaluate arytenoid function or to look for gross abnormalities of the epiglottis or soft palate," said Dr. Jim Morehead of Equine Medical Associates, which provided yearlings' medical records for the study. "This confirms that the information gained from endoscopic examinations of standing, at-rest yearlings is pertinent to the future performance of the horse.

"But many variations from normal in the soft palate and epiglottis do not adversely affect racing performance."

That finding will be of interest to sellers who have had yearlings criticized on the basis of an immature epiglottis or an apparent tendency to displace the soft palate during the endoscopic exam. Those factors, according to this study, do not necessarily indicate that the horse, when mature, will perform worse.

"We do recognize that if a horse has very serious palate problems or a very abnormal epiglottis, you have to use common sense," said one of the study's authors, Dr. John Stick, chief of staff of Michigan State University's large animal hospital and a researcher who has studied equine soft-palate problems extensively. "But people should be conservative in their judgments in looking at palatal and epiglottic abnormalities in yearlings and understand that these abnormalities in a yearling may have nothing to do with that horse's eventual racing performance.

"But people can also have more confidence now in the recommendations they make based on the gradings of arytenoid cartilage movement. They have guidelines backed up with scientific data when they need to make those judgments."

Animal anthrax

The dispersal of anthrax through the postal system has brought attention recently. But anthrax, mainly a disease of livestock and wildlife, is a potential naturally occurring problem in horses.

In July, anthrax hit Texas, infecting two men as well as horses, deer, and cattle in Uvalde and Val Verde counties.

"The disease often occurs after we have periods of wet, cool weather followed by a several weeks of hot and dry conditions," said the Texas Animal Health Commission's Dr. Dan Baca. "When livestock graze in an affected pasture, they can ingest the spores that are on the grass or ground."

According to the United States Department of Agriculture, anthrax also can spread via streams, insect bites, and contamination from the waste of infected animals.

In horses, anthrax symptoms include fever, colic, septicemia, and enteritis, if the horse ingested the spores. If the horse was infected via insect bite, symptoms can also include hot, painful swellings under the skin at the site that then spread to the throat, lower neck, and abdomen.

Fortunately, livestock owners have been able to vaccinate their animals against anthrax for decades; the most commonly used vaccine was developed in 1937. But, for most parts of the country, the anthrax vaccine is not considered routine for horses. It should not be given to horses undergoing antibiotic treatment.