In foaling season just concluded, disease that kills foals appears to have been the second worst ever

University of Kentucky chart, with labels placed by Midway Messenger; click on it to enlarge.

The original version of this story, in May, was based on data that were misinterpreted by the Messenger, and it has been revised. We apologize for any confusion or inconvenience.

By Hayley Burris

University of Kentucky School of Journalism and Media

The infection that causes Thoroughbred foals to be aborted or born dead or underdeveloped is slacking off as this year’s foaling season nears its end, but it appears to have caused the second most documented cases ever.

Nocardioform placentitis can cause the placenta to detach, causing premature birth or stillbirth.  Foals that live usually have a compromised lifespan due to being underdeveloped or undersized. 

Every year, at least a small number of horses in Kentucky are affected by this infection but this year the numbers set an apparent record, with 310 cases through April.207 cases through May. That was second only to the 328 cases in the 2010-11 foaling season.

University of Kentucky chart

Woodford County had 21 cases this season.  Fayette County has had 163 cases and Bourbon County has had 13. Cases in other counties were Scott, 5; Harrison, 2; Oldham, 2; and Shelby, 1.

The Midway Messenger was unable to identify any particular Woodford County farms with cases. Research suggests it is likelier on larger farms.

In a typical season, Kentucky has 20 to 50 cases, according to the Maxwell H. Gluck Equine Research Center at UK. The cause of the infection remains unknown, and so does why there have been so many this year.

The Gluck center is researching that through submitted placentas, mares, and foals, with the help of $132,000 in emergency funding from the foundation that supports the center. The money comes from an endowment created to address such emergencies.

“We are very fortunate to have had the help of local practitioners and farm managers/owners to obtain samples of normal and affected placentae for research given the extremely difficult situation we all find ourselves in with the coronavirus pandemic,” Emma Adam, an assistant professor in the College of Agriculture, Food and Environment said in an email.  “Our vets and farms have been amazing in still submitting samples in spite of these challenges.”

Kentucky tends to have more documented cases of nocardoioform placentitis, because it produces about 40 percent of the nation’s foals, but also because it does more research on horses, UK professors say.