Two “syndromes” that began near the end of the third week of April are causing 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 only starting Derby week 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 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