Evidence of West Nile virus (WNV) was found in 35 aborted fetuses in Kentucky since July of 2002, according to Lenn Harrison, VMD, head of the Kentucky Livestock Disease Diagnostic Center in Lexington. “We have handled about 400 aborted fetuses and tested them, so this is less than 10%,” he reported on Feb. 4. He emphasized that WNV has not been known to cause abortion in mares; therefore, these preliminary tests do not necessarily indicate that WNV caused the abortions. The University of Kentucky reported that other states with higher incidences of WNV in their equine populations have not reported any association of WNV with equine abortions.

Maureen T. Long, DVM, PhD, assistant professor of large animal veterinary medicine at the University of Florida’s College of Veterinary Medicine, has an active research program on the clinical aspects of WNV infection in horses. Thus far, very informal inquiries at this stage have not elicited evidence of increased abortions in Florida. But she says that the Florida Thoroughbred industry, Florida pleasure horse breeding groups, and the University of Florida are looking at breed registry information and fetal abortion submissions. Long will also work with Kentucky researchers to follow some farms affected by West Nile virus in terms of reproductive losses.