At the end of April in Kentucky, we suddenly started seeing a large number of foals with an unusual combination of signs admitted to the Hagyard-Davidson-McGee Neonatal Intensive Care Unit (NICU). Most were slightly premature--maybe a week or two before due dates--and had a history of a "red bag" delivery or apparent premature separation of the placenta. We fully expected these patients to have problems associated with birth asphyxia (lack of oxygen). After several affected foals were admitted, we started to see a pattern emerging. Most had extremely low white blood cell (WBC) counts, low blood glucose levels, respiratory problems, and unusual neurologic signs (more severe than typical for birth asphyxia or "dummy foal" syndrome). The worrisome thing was that many were dying; in the past we had successfully treated most foals with birth asphyxia.

Early on, we were called to do fetal ultrasounds. These exams of late-gestation mares generally showed normal findings, but many of these mares later lost their foals.

It wasn't long before the number of foals admitted to the hospital became so massive that we were hard pressed to find room for all of them. We made stalls out of the hay rooms, recovery rooms, and in aisleways. Everyone worked overtime, and took the losses very personally. The description of the scene being like a M.A.S.H. unit was appropriate. We were at war. There was a growing panic in the industry. There weren't any answers to explain what we were seeing.

While everyone was in shock at the number of late-term foals affected, we soon learned that there was much more to the story. The field veterinarians began reporting large numbers of early fetal deaths and an unusual ultrasound appearance of placental fluids in some pregnancies that later progressed to fetal death. The University of Kentucky's Diagnostic Center was the focal point, as both groups of foals were ending up there. The typical battery of tests were failing to reveal a common cause, such as a virus.

For about three weeks this devastation continued at full-bore. There was world-wide recognition of the problem, and all eyes were on Kentucky. Owners, farm workers, and hospital personnel recognized this was something of crisis proportions, but found it hard to resign themselves to the fact they couldn't save everything. And still, no one had an answer. That was the real stress of it all. There was no answer to explain what was wrong with our neonatal patients. No answer for the early fetal losses.

Our approach to medicine is based on evaluation of clinical problems and laboratory data and an understanding of the mechanisms of disease. Things just weren't fitting together with these foals.

Then, other problems began to be detected. We saw an unusually large number of horses with pericarditis (an inflammation of, and fluid accumulation within, the sac surrounding the heart). In any other year, we might see two or three pericarditis patients. We saw eight cases in one day at the peak, and the total is around 50 in our hospital alone.

We also saw foals and adult horses with hemorrhage and inflammation in their eyes--uveitis. Our routine workups for these problems included searching for some infectious agent. In these horses, nothing consistent was found.

The industry-wide informational meetings at least offered a time for the community to come together and talk things over. The initial ideas put forth were plausible...the mycotoxin theory seemed to fit. There was no solid evidence, but it seemed like something that people could try to do something about. Soon, however, laboratory testing came up empty on that theory.

Early on, people were talking about the large number of caterpillars this spring. I think we all pushed that idea aside, but Dr. Lenn Harrison at the Diagnostic Center left no stone unturned, and he found something with the caterpillars. Initial testing on fetal tissues showed low levels of cyanide. Finally, some evidence to build on! The final answer may be in the future, but finding a cyanide connection is a good start.

In the last week of May, things started to slow down in the hospital. Everyone--from the veterinary nurses, doctors, and van drivers to farm personnel--are exhausted. Is the danger over? We certainly hope so. But there are still a lot of unanswered questions. We are still seeing cases of pericarditis. We all hope that answers will be found. The world is watching.

About the Author

Fairfield Bain, DVM, MS, Dipl. ACVIM, Dipl. ACVP

Fairfield T. Bain, DVM, MS, Dipl. ACVIM, Dipl. ACVP, specializes in internal medicine and pathology. He is an equine technical services veterinarian at Merck Animal Health.

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