Excessive Foal Loss Great Concern to Central Kentucky Farms

Two "syndromes" that began near the end of the third week of April are causing Central Kentucky farms to lose an excessive number of foals and fetuses due to an as yet unknown cause. The first syndrome results in what mare owners know as "red bag," or premature placenta separation where the placenta comes out before the foal, often causing the foal to suffocate if the birth is unattended. The second syndrome was discovered around May 1 when veterinarians began routine 60-day fetal checks and discovered that many mares either were empty (not pregnant), or were in the process of losing their pregnancies. Some farms have experienced losses ranging from 25-75% of next year's foal crop. And there is no evidence that this problem is slowing down.

It is unknown at this point how many foals/fetuses have been affected, but Dr. Doug Byars at Hagyard-Davidson-McGee veterinary firm in Lexington said that on Kentucky Derby Eve alone there were 14 "red bag" foals admitted to their clinic. Those foals have a high mortality rate, with only about 50% being saved.

"Some mares will start to foal standing up," he said, pointing out the abnormal occurrences associated with the syndrome. "Some foals are early, some at term, and some are overdue. The mares usually have developed an udder, but some are agalactic (don't develop an udder or produce milk normally). The foals don't want to breathe. There are a lot of stillbirths. Many of the foals that make it to the hospital have low white counts (the blood cells that fight infection), are septic (system-wide infections), and dehydrated."

Byars said no "bugs" have been grown from any samples taken, and while this syndrome is not a classical fescue toxicosis, it could be something similar.

There are many theories as to the cause of these two seemingly related problems, ranging from blaming this year's extreme tent caterpillar crop to mycotoxins in the grass. Byars said the mycotoxin theory is the one most plausible due to this year's unusual weather conditions.
"We went from spring to summer with a freeze in between, and that is good for fungus growth," explained Byars. "The opportunity for fungus proliferation is extremely high, and the concentration of the toxins in the dried-out grass could contribute to the problem."

Byars said current recommendations are to treat every foaling mare as a high-risk foaling situation. Veterinarians are administering domperidone and taking other steps to counteract some of the symptoms associated with the foaling problems.

He also suggested mowing pastures in spite of the drought conditions that currently exist in the region. "Many people stopped mowing when conditions got dry," said Byars. "I am suggesting mowing although the damage may already be done.

"The statistics of losses are beyond what I've ever recognized in my 18 years in Kentucky," Byars added. "A few mares have normal foals. When I went to one farm (May 6) and checked one late-gestation mare, she was okay and so was the fetus. But that farm lost two foals that morning to stillbirths."

Byars stressed that the symptoms associated with these two syndromes do not point toward an infectious/contagious disease. Rather, it looks more like an environmental cause. He also said there hasn't been widespread use of any new product to which these losses can be attributed.

"We need some rain, and we're getting some now," said Byars. "If the cause is mycotoxins in the grass, that will be hard to show and will require a lot of agronomy, diagnostics, and other specialists working together."

Text of UK Veterinary Science Department Memorandum on Late Term Abortions and Early Fetal Deaths