Since December 3, 15 horses have become acutely ill at a Quarter Horse breeding farm in Vermilion Parish County, Louisiana. Two horses died within 48 hours of onset of clinical signs. Ten horses were euthanized within the same time frame due to rapid decline. Two horses are still alive at the LSU veterinary teaching hospital.

The clinical signs began as muscle tremors in the postural muscles. The tremors quickly progressed to the whole body. The horses would repeatedly go down and display signs of agitation. Within three hours, the horses progressed to lateral recumbency. They were unable to roll into sternal or stand. A few of the horses demonstrated decreased tongue tone. Motor function to all four limbs is intact. The horses will sometimes paddle violently while laterally recumbent, but they are responsive to voice and touch during these episodes. Their temperatures are normal and heart rates are moderately elevated with no arrhythmias or murmurs.

A preliminary investigation into the incident has suggested that contamination of a common feed source is responsible. Botulism is the suspected culprit. Alfalfa cubes produced in Colorado are a potential source.

Owners of horses displaying similar symptoms should contact their veterinarian immediately. Veterinarians should report any suspected positive horses to Dr. Rose Baker at the Veterinary Teaching Hospital at Louisiana State University.

EDCC Health Watch is an Equine Network marketing program that utilizes information from the Equine Disease Communication Center (EDCC) to create and disseminate verified equine disease reports. The EDCC is an independent nonprofit organization that is supported by industry donations in order to provide open access to infectious disease information.