Ask an Expert

Rabies in Horses

September 7, 2010

Exposure to just one rabid animal could be fatal to your horse.

Question:

I’d like to know more about the effects of rabies in horses. Where can I get more information?

Answer:

For the answer, Daily went through some recent America’s Horse archives and found a great story to get you pointed in the right direction. Consult your veterinarian in any event your horse needs medical attention.

Rabies 101

From America’s Horse magazine

Dr. Ann Dwyer, a veterinarian in New York, took the call: “Our mare is bellowing like a pig and acting strangely,” the client said.

“On arrival, I found the mare in a pen. Long ropes of drool dripped from her mouth,” Dr. Dwyer wrote in an article on www.thehorse.com. “She was tossing her head, flinging saliva everywhere. She had chewed a large hole in one leg through the skin,” Dr. Dwyer says. “Her aggression was terrifying – she would attack anyone and anything that came near her. When I asked about her rabies status, I was told she had never been vaccinated. Strongly suspecting rabies, I convinced the family to put her to sleep. Subsequent testing confirmed the disease.”

That’s the story of just one of three equine rabies cases Dr. Dwyer has handled as an American Association of Equine Practitioners-approved veterinarian at the Genesee Valley Equine Center in Scottsville, New York, a state in which there have been more than 50 reported cases of horse rabies in 20 years.

“All were very different, illustrating that rabies can look like anything,” she says.

Skunks, foxes, bats and raccoons are the main wild animals that transmit rabies, Dr. Dwyer says.

“Wild animals with rabies behave abnormally, and as horses are curious, it is easy to imagine how they can be bitten by a rabid wild carrier,” she says. “A single bite can transmit enough virus to kill.

“Once a horse shows signs of rabies, it invariably dies within a few days,” she says. “Early signs range from colic and lameness to depression and agitation. There is no treatment. Horses with rabies are a great risk to their handlers, as saliva from an affected horse carries virus that can potentially transmit the disease to a person.”

That’s why it’s still important to vaccinate your four-legged best friend against the disease every year, according to AAEP, which lists a rabies vaccination on its recommended annual vaccination schedule.

And because rabies can be transmitted from animals to humans, Dr. Dwyer, the families and handlers of the three rabid horses that she has seen had to undergo post-exposure rabies vaccinations.

Dr. Dwyer’s second case was very different.

“This horse was seen at a routine appointment because she just wasn’t right,” Dr. Dwyer says. “I did a physical exam and found nothing major other than a mild fever and dull attitude. I opened her mouth during the exam and handled her tongue and gums. I took some blood and prescribed anti-inflammatories. Overnight, the mare lost the ability to swallow, and she was getting wobbly.”

The mare was sent to Cornell University, but her condition deteriorated, and she was euthanized. She had never been vaccinated for rabies and was found positive for the disease.

Dr. Dwyer’s third rabies case involved a 3-year-old gelding.

“Our practice’s intern found the horse was hot, had signs of colic and had some incoordination in his hindquarters,” Dr. Dwyer says. “We monitored him for several hours; his signs varied – he would fall down and act painful and wobbly, get up and act semi-normal, then repeat the cycle. Over time, he got worse,” and that evening, he went down.

Dr. Dwyer discovered that the horse had not had a rabies vaccination because rabies was not considered a problem in the state where the current owner had purchased him.

“The horse was euthanized that night and confirmed rabid the next day,” Dr. Dwyer says. “Eight people who handled the horse – including me and our intern – pursued post-exposure treatment.”

The Centers for Disease Control and Prevention reports that horses account for less than 1 percent of all rabies cases in the United States.

Signs of rabies can vary between species. For example, cattle exhibiting the “furious” form of rabies can attack people and other animals. On the other hand, infected animals can exhibit minimal behavioral changes in the “dumb” or paralytic form of the disease.

Know the Signs

According to AAEP, physical signs of rabies can include:

  • Fever
  • Anorexia
  • Blindness
  • Dysphagia
  • Hyperesthesia (manifested as self-mutilation)
  • Muscle twitching
  • Lameness
  • Paresis and/or ataxia
  • Incontinence
  • Ascending paralysis
  • Sudden death

A single case of rabies during an event can put thousands of people and animals at risk. In 2006, the CDC notified more than 150,000 people who attended the Tennessee Walking Horse National Celebration of potential rabies exposure after a case was confirmed during the event.

Immunize

AAEP recommends that immunizations begin when a foal reaches 6 months of age, followed with a booster dose in four to six weeks. Horses should then receive boosters at annual intervals starting at 10 to 12 months of age. Broodmares should be vaccinated four to six weeks before their delivery dates.