The West Nile Virus is a viral disease that causes meningitis or encephalitis in a variety of mammals, including horses. It originated in remote areas such as Africa, West Asia, Eastern Europe, and the Middle East but was not detected in the Western hemisphere until 1999, in New York City. The West Nile Virus is a potentially fatal disease that has affected thousands of American horses since then. As a matter of fact, it’s been estimated that horses account for 96% of all non-human cases of West Nile Virus.
The virus has been traced to the mosquito pest. The principal transmitter of West Nile Virus is the Northern House Mosquito (Culex pipiens). Mosquitoes generally become infected after taking a blood meal from an infected bird and then spread the disease to other hosts. The mosquito’s immune system enables her to continue spreading the virus without becoming ill herself, making the mosquito a carrier that is able to infect a variety of animals during her life cycle.
Although approximately 33% of horses that exhibit signs of West Nile Virus infection die, the vast majority do not get sick, and in fact, many show no symptoms of all. Those that do exhibit symptoms generally show a combination of the following signs that may indicate encephalitis:
· fever
· weakness of hind limbs
· paralysis of hind limbs
· impaired vision
· ataxia (weakness)
· head pressing
· aimless wandering
· convulsions (seizures)
· inability to swallow
· walking in circles
· excitability
· coma
It is expected that the West Nile Virus will remain a serious disease threat in the future, which makes mosquito control incredibly important.
How to protect your equine friend from the West Nile Virus
One of the best ways to manage the West Nile Virus is to maintain adequate pest control and fly control. This can be done by reducing mosquito breeding areas and by keeping areas around your stable clean and dry. Insecticides can be an extremely valuable tool in the fight against the West Nile Virus. Permethrin is a highly effective chemical that is considered to be safe as an insecticide, acaricide, and as an insect repellent. Although it is considered to be highly toxic to cats and some aquatic life, permethrin is safe for humans and other animals, including horses.
Another option to consider is to vaccinate your horses against the virus. Many veterinarians recommend vaccinating all horses that reside in North America, starting when a foal is about 3 to 4 months of age. From there, it’s suggested that a horse go through 4 doses of vaccination by the time that they’re a year old and then annually for the rest of their life. Vaccinating your horse is a simple matter that greatly increases survival rates if the animal is bit by an infected mosquito.
In addition to insecticides, repellents, and vaccinations there are a variety of common sense measures that you can take to protect your horse from mosquitoes this summer.
· Replace the water in dishes, birdbaths, and other containers regularly. These are the areas that female mosquitoes like to lay their eggs and timely attention to them prevents eggs from hatching.
· Drain any standing water around your stable or other farm buildings.
· If you have a pond, stock it with fish that feed upon mosquito larvae.
· Place fly traps or mosquito dunks near areas where horses live.
· If your horse spends a great deal of time in the pasture, consider using a fly mask to protect him from mosquitoes and other biting bugs. These pieces of clothing fit over the horse’s face, and the fine mesh allows him to see out while keeping flies and mosquitoes from landing in his eyes or biting. There are also fly sheets and boots available for horses that can help get rid of flies.
As you can see, the West Nile Virus is a very serious disease that is easily preventable. Proper pest management procedures are crucial for keeping your horse safe during the hot, summer months when fly populations are at their very highest. Remember, mosquito and fly prevention is not a matter of just spraying pesticides around and hoping for the best. One should always stay on top of mosquito populations by reducing breeding areas whenever possible. Keep an eye out for signs from your horse like foot stamping and head tossing, which can indicate that mosquitoes or other pests are biting and use insect repellent if necessary. Keep horses indoors during the twilight hours when mosquitoes are at their most active or cover them if you cannot keep them inside. Above all, make sure to provide your horse with regular visits to your veterinarian’s office and ask what you can do to keep your animals safe this summer from the West Nile Virus.