West Nile virus is a mosquito-borne disease of increasing concern in many areas of the United States. According to the American Association of Equine Practitioners, the virus has been identified in all U.S. states as well as Canada and Mexico. It primarily affects birds, but mosquitoes can transfer the disease to other animals.
The virus is of particular concern for horse owners as it can lead to arbovirus encephalitis and meningitis. The mortality rate in horses is estimated to be around 30% once symptoms appear and early treatment is important. It’s important to know the signs of infection and prevent future infections.
Signs and symptoms: Symptoms usually begin to appear within two weeks after exposure. Though these symptoms don’t necessarily indicate a West Nile virus infection, they should be checked out by a veterinarian. This is not a comprehensive list:
- Muscle tremors
- Excessive tiredness
- Tripping or stumbling (beyond what is normally seen for the individual horse)
- Paralysis in various muscles
- Vision problems
- Disorientation and circling
- Weakness in hindlimb
- Head pressing
Treatment: Once a horse is infected, there is no official treatment other than supportive veterinary care. Veterinarians may use different techniques such as reducing brain swelling or intravenous fluids to keep the horse hydrated. At the current time, there are no specific antiviral medications for this disease. Most horses that recover do so within a week, but may show neurological problems for several weeks afterward. To learn more about avoiding headstall hassles, check this post.
Prevention: The best way to fight West Nile virus is to prevent it from infecting your horses. There are vaccines to prevent the disease as well as equine encephalitis, a condition often caused by the virus. Your veterinarian can tell you more about these vaccines and when to administer them. It’s getting winter now and in northern states, it won’t bother you much the coming months until you let your horses enjoy springtime again, but in southern states, the virus might be causing trouble throughout the year, especially in mosquito-rich environments.
Other ways to reduce your horse’s risk of contracting the virus include:
- Reducing standing water where mosquitoes can breed or reducing horse activity near these areas.
- Keeping birds from hanging out or nesting in the stable or pen areas.
- Reporting dead birds, especially corvids and raptors, to your local department of public health.
- Keeping horses indoors during peak mosquito times such as dawn or dusk.
- Using fluorescent lights in the stable or keep lights off at night and apply normal horsemanship.
- Using insect repellent or other techniques to reduce insect bites on the horses.
While the chance that a horse will get West Nile virus is currently low in the United States, it’s always best to take precautions with mosquitoes at all times. You’re never done learning. Mosquitoes and other biting insects are all potential vectors of diseases. Reducing these insects can potentially improve your horse’s health in many ways.