Equine Rabies in Marion County
On Sunday, November 20, 2011 a yearling Thoroughbred filly was admitted to the Equine Medical Center of Ocala with a two day history of high fevers, aggressive behavior and symptoms consistent with colic. As a result of her behavior at presentation, this horse was considered to be a rabies suspect. Precautions were immediately taken to reduce the risk of exposure to our staff. Within 12 hours of admission, the filly became more aggressive towards our medical staff and also began to bite her own limbs. As this behavior escalated, we sadly decided that euthanasia was the only humane thing to do for this filly. Post-mortem testing, performed at the Florida Department of Health in Jacksonville, FL, found the horse to be positive for the rabies virus.
Rabies is primarily a disease of wildlife, found mostly in raccoons, skunks, foxes and bats. Turn-out adjacent to wooded areas, and in pastures that are not regularly maintained, may lead to a greater risk of equine exposure; however, the rabies positive horse treated at EMCO had only limited access to turnout. This demonstrates the importance of vaccination against rabies in all horses, regardless of the environment in which the horse is boarded. In horses, the acquisition of rabies is usually associated with bites on the muzzle, face and lower limbs. Following the bite, the virus migrates to the brain, through the nervous system, where it causes fatal encephalitis. Rabies can be difficult to diagnose as clinical signs can be variable and are often similar to several more common diseases. Initial signs can include behavioral changes, dullness and depression. Other clinical signs include salivation, anorexia, colic, difficulty swallowing, lack of coordination, aggressive behavior, self mutilation and excitability. Following the onset of clinical signs, death typically occurs within 3-5 days. Virus shedding is highest when the horse is exhibiting clinical signs.
Currently no laboratory testing exists to confirm rabies on a live animal; diagnosis can only be confirmed post-mortem. A horse owner should call his /her veterinarian immediately if he/she suspects that their horse could have rabies.
While rare in horses, rabies is 100% fatal, but the disease can be easily prevented with a proper vaccination schedule. Rabies vaccine is inexpensive and highly effective. Please take this opportunity to consider updating your horse’s vaccination status. The American Association of Equine Practitioners (AAEP) recommends that an annual rabies vaccination be a core vaccine for all horses.
J. Barry David, DVM, Diplomate ACVIM
Marshall Stevens, DVM