11/23/2001 12:00AM

New theory on destructive syndromes

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LEXINGTON, Ky. - As stallion and mare owners prepare for the 2002 breeding season, many wonder whether the syndromes that affected their horses this spring will repeat next year. No one has definitively established a single cause for the mare reproductive loss syndrome, swelling of the heart sac, and eye inflammation that appeared in 2001. But one of the front-line veterinarians who dealt with the heart symptoms, has a theory that may shed some light on at least a portion of the spring's damaging syndromes.

Dr. Johanna Reimer, a veterinarian at Lexington's Rood and Riddle Equine Hospital, who is board-certified in equine internal medicine and cardiology, was one of many field veterinarians, researchers, and agronomists caught up in the effort to help horses and identify the cause of the spring syndromes.

In the absence of an identifiable pathogen, researchers have offered a number of theories, ranging from cyanide-carrying caterpillars to poison hemlock to the so-called "witches' brew" of fungi and mycotoxins that might have occurred during the spring's unusual pattern of drought, freeze, and heat. But Reimer's experiences in dealing with pericarditis - the swelling of the sac around the heart that was one of the spring syndromes - have led her to theorize that a single fungal organism, first on its own and later by producing mycotoxins, potentially could be responsible for the four syndromes vets saw this spring: early fetal loss, stillbirths or ill foals, pericarditis, and endogenous panophthalmitis (a form of eye inflammation).

Reimer and her colleague Dr. Claire Latimer found little crossover among the symptoms and noted that mares who developed pericarditis did not seem especially predisposed to reproductive losses, suggesting that a single toxin did not cause both syndromes. It could indicate that the syndromes were caused by two mycotoxins occurring in the same time frame, but Reimer points out that, under natural conditions, toxins most often do not cause inflammatory responses like pericarditis and panophthalmitis.

Instead, Reimer suggests the key to the various syndromes might be because of the unusual weather's effects on a single fungus.

"It may well be one and the same fungal organism," she said. "But if the fungus was healthy at one stage, it caused horses to come up with eye and heart symptoms. When it was stressed, the mares got exposed to mycotoxins, which could have caused the abortions."

Reimer said some of the still-born and ill foals also showed signs that, while not definitive, can occur with some fungus-produced mycotoxins: goiter, hemorrhaging in the eye, and high white blood cell counts indicative of immunosuppression.

Reimer hasn't conducted a study of her informal theory. But she has saved blood samples taken from some of her clients' horses who had pericarditis and eye problems and is awaiting word from other researchers who are taking soil samples on affected farms that might show evidence of an unusual springtime fungal bloom. If they do, Reimer said the next step would be to screen the blood samples for antibodies to the identified fungi, then to determine what mycotoxins those fungi produce that might create a link to MRLS.

For now, Reimer's theory is just that: another hypothesis. And she, like most central Kentucky breeders, doesn't think there's any endemic problem with the area's grass or soil.

"In fact, I've just bought 30 acres myself," she said.

Findings presented at Cheltenham

British researchers have found that galloping racehorses for at least one furlong for every seven furlongs cantered should decrease the risk of racing injury among steeplechasers and hurdlers, according to a study presented at a recent veterinary seminar at jump racing's famed Cheltenham Racecourse.

The seminar also featured results of a nine-year study of racing fatalities. The study determined that the age at which a horse begins his career and the distance at which he debuts are major factors in serious injury.

The seminar yielded recommendations to shorten flat races for National Hunt horses and to card more schooling races for steeple-chasers in an effort to prevent serious racing injuries.

Other presentations at the seminar reported that 80 percent of fractures in flat runners occur during training hours and that studying bone-cell activity during training can help trainers develop programs that encourage fracture-resistant bone growth. One study, presented by Dr. Roger Smith, found that incorporating brief sprints, which gradually increase from a quarter-mile to a half-mile, into training twice a week promoted strong bone growth.

The seminar also featured presentations about using objective gait and conformation analysis to predict performance; the role of racing surface conditions in performance and injury; and contributing factors in race falls among National Hunt horses.