The farm in the video is located on a moderately active road. Just through the tree-line behind the pasture is the residential area of the small town in which we live. Although the owner of the horses has always vaccinated the horses against rabies (per our recommendation—rabies is included as an American Association of Equine Practitioners’ recommended core vaccines), he never expected his horses to be exposed.
The owners were walking their young children down the driveway when they noticed a fox acting unusually in their field. The fox stalked and then attacked their gelding, Jet. Foxes normal prey is small rodents and birds and wouldn’t pay any attention to a horse other than to avoid it.
When the fox died, his body was sent to the Alabama State Health Department, which confirmed the fox was positive for rabies. Immediately after removing the dead fox, both Jet and his pasturemate were closely examined for any wounds the fox might have inflicted. Fortunately, none were evident. However, fox have small teeth, so when the fox was confirmed rabies positive, we immediately boosted their rabies vaccines and kept them under observation.
Why were we so concerned that Jet and his friend were exposed to a rabid fox?
Rabies is caused by a virus that can affect most warm-blooded animals. As well as our furry pets, this also includes humans. It causes encephalitis (inflammation of the brain) that is almost always fatal. Even now, we can prevent rabies well through vaccination, but once clinical signs develop, the disease nearly always results in death due to the severity of brain damage caused by the virus.
Humans are most commonly infected by affected pets, which is why most municipalities in the United States require regular vaccination of dogs and cats. However, humans can also be exposed from handling affected wildlife.
The virus is shed in the saliva and can enter the body either through wounds (i.e., a bite), by breathing high concentrations of the fresh secretions (rabid animal breathing in your face), or by ingesting affected tissues (so your dog or cat can potentially develop rabies from eating affected wildlife that’s died recently). The virus can’t survive in dried saliva so transmission away from the affected animal is unlikely.
We kept an eye on Jet and his friend for several months after this incidence before declaring them clear. That’s because when rabies first enters the body, it must travel up the peripheral nerves to the central nervous system. During this incubation period, most infected animals show no clinical signs. The incubation period can be highly variable (as short as a few days or as long as a year) and is influenced by the pathogenicity of the virus strain, the size of the dose in relationship to the size of the animal, and the distance from the central nervous system that the exposure occurred.
Because Jet and his friend showed no noticeable wounds, any exposure that they got was likely to be a very low level. And, because the fox bit at Jet’s back foot, any exposure was very far away from his central nervous system, so we expected that any virus would take a long time to reach it.
Once the virus reaches the central nervous system, the disease progresses rapidly, with death following the onset of clinical signs within five to 14 days. Clinical signs will vary with the area of the brain most affected by the virus. Animals can show changed behavior (either unusual aggression or depression), incoordination progressing to paralysis, seizures, and in some cases, sudden death without previous signs being noted. Early signs can be difficult to differentiate from lameness, in some cases, as the virus causes inflammation in its journey along peripheral nerves. Jet and his friend never developed any signs consistent with rabies and are still doing well today.
Although we don’t often think about our horses being exposed to rabies, this virus is much more prevalent than is commonly perceived in the United States. In 2015, the Center for Disease Control reported 14 cases of rabies in horses or mules down from 25 cases in 2014. Rabies is endemic within the United States, Canada, and western Europe. Frequent outbreaks are seen in Central and Southern America. In endemic countries, the disease is maintained by strains that are adapted to a certain wildlife species. The most common reservoirs species in the United States are skunks, raccoons, red foxes, and bats.
Protecting You and Your Horses
How can we avoid contracting rabies?
- Vaccinate your pets for rabies as recommended by your veterinarian. Recommendations will be different depending on the risks in your area and your and your pets’ lifestyle.
- Don’t handle or approach wildlife, especially if the animal is acting unusually. Remember, humans are large predators, so normal/healthy small wildlife do not approach us willingly.
- Don’t allow your pets to play with wildlife. Keep dogs on a leash in wilderness areas and keep cats indoors if not supervised.
- Don’t feed or encourage wildlife to hang out around human habitations. The closer reservoir species stay to human beings, the higher the probability a human will be exposed to rabies. Remember, animals might not be showing clinical signs of disease yet but could still have enough virus shedding to affect you or your unvaccinated pets.
- If you or your pets do get bitten by wildlife, contact your public health officials immediately (and your veterinarian for your pet). If the wild animal is dead, it should be submitted for necropsy examination to confirm if it is rabid so appropriate post-exposure treatment can be begun to prevent you from developing rabies. State and local rabies consultation contacts can be found at https://www.cdc.gov/rabies/resources/contacts.html.
- If you work in a field where you have frequent exposure to wildlife or unknown pets, experts recommend you have pre-exposure vaccination.
Rabies is a deadly virus that causes severe neurologic disease that can affect mammals, including humans. Talk to your veterinarian about the risk to your horse, and avoid any wild animals exhibiting abnormal behavior. If you, your horse, or a pet is bitten, contact your animal health authorities immediately.
Editor’s note: Thank you to the Ellis family of Columbiana, Alabama, for sharing this video that shows the behavior of a rabid fox.
- Rabies; Centers for Disease Control and Prevention: Rabies homepage; https://www.cdc.gov/rabies/prevention/index.html
- Rupprecht, Charles. “Overview of Rabies.” Merck Veterinary Manual online. Copyright 2016. http://www.merckvetmanual.com/nervous-system/rabies/overview-of-rabies.
- “Rabies.” Smith, Mary O. (consulting editor). Large Animal Internal Medicine third edition, Bradford P Smith editor, Mosby, Inc, 2002; pp.892-895.
- Sommardahl, Carla S. “Rabies.” Equine Internal Medicine – Second Edition. Reed, Bayly, & Sellon editors, Sauders, 2004; pp. 644-646.
About the Author
Kristin Varga, DVM, is a veterinarian at Southern Equine Services in Columbiana, Alabama.
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