Rabies in Horses

Filed Under: Horses, Diseases

Rabies is a virus that may infect the central nervous system of any warm blooded animal. Rabies is typically spread by the saliva from infected animals. Horses are most likely to contract rabies by the bite of a wild carnivore, bats, or unvaccinated cats. Rabies is essentially 100% fatal once clinical signs attributed to the disease are exhibited.

In the year 2001 there were nearly 7,500 cases of rabies that were reported to the Centers for Disease Control and Prevention in the US. Of those cases, 51 were members of the Equine Family.

The rabies virus affects the central nervous system causing an encephalopathy (disease of the brain) and will eventually lead to the death of the infected individual. The incubation period may last as long as four months. This incubation period is dependent upon the site of the original bite and amount of virus present in the bite itself. The virus first multiplies at the site of the wound and later travels up the peripheral nerves to the brain and salivary glands. During this incubation period the horse will exhibit no signs of illness.

There are two clinical forms of rabies, one being the furious or aggressive form and the other being the paralytic or dumb form. Horses with the furious form of rabies will exhibit aggressive behavior and may charge and strike out at humans or other animals. These horses may have tremors, convulsions and be excessively excitable to external stimuli. In the paralytic or dumb form of rabies the horse may have difficulty swallowing, be depressed, have excessive salivation, and be unable to eat. The head may become tilted, the horse may begin circling, or show a lack of coordination gradually leading to paralysis. Death usually occurs within a week of showing clinical signs.

Most human infections of rabies are obtained from human interaction with companion animals or infected bats. Just think about all the time you spend interacting with your horse’s mouth. You are constantly placing bits in their mouths or removing them after riding, which is a lot of exposure to saliva. In May of 2006, three horses in Michigan died of rabies that was obtained secondary to skunk bites. All of the people in contact with these horses had to undergo costly post-exposure rabies treatment. Also, in 2006, about 150,000 people attending the Tennessee Walking Horse National Celebration in August were at risk of being exposed to rabies through contact with the saliva of a gelding stabled there. That same gelding was later euthanized and found to be rabid by the Centers for Disease Control.

Rabies can be prevented by limiting exposure to wild carnivores and by vaccination of barn cats and other pets. When wild animals such as skunks and raccoons appear overly friendly, especially during daylight hours, be wary! Skunks and racoons are usually nocturnal. An Alabama study revealed that as many as 33% of the skunks and raccoons that are active during the day may be rabid. Do not leave food out where it may attract wild animals. Move horses away from a threat whenever possible.

The American Association of Equine Practitioners recommends that horses in endemic areas be vaccinated against the disease every year. Most States in the US now require rabies vaccinations for companion animals. Several Rabies vaccines are available for use in horses, including Imrab®, manufactured by Merial.

Topics: contagious diseases, rabies

Symptoms: aggression, circling, difficulty eating, hypersalivation, paralysis

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