Unless you have been living under a rock, you have probably heard about West Nile Virus and know it is a threat to your horse. How, then, do you protect your horse from this and other mosquito borne illnesses? By reducing mosquitoes around your stable, helping your horse avoid the ones that remain, and vaccinating your horse against the illnesses common in your area.
According to the United States Department of Agriculture, there are four types of encephalitis that strike horses in the United States and Canada. These are: 1)Eastern Equine Encephalitis, 2)Western Equine Encephalitis, 3)Venezuelan Equine Encephalitis, and 4)West Nile Virus. All four strains have similar symptoms. Most horses that contract them have a mild flu-like illness. Some horses have fever, headache, and a sore throat. The most severely affected horses have a sudden fever and headache followed by convulsions, coma, and even death. According to the Texas Animal Health Commission, even horses that survive the severe version of these illnesses are usually brain damaged and unfit to ride.
Because all of these diseases are viruses, there is no treatment for them. Supportive care, such as fluids, rest, support when the horse cannot stand, and love are the only options currently available. This makes prevention of prime importance.
Prevention can be broken down into three areas: reducing the source, avoiding the source, and vaccination. Since these diseases are spread by mosquitoes, it is important to make sure there is no where for the mosquito to breed around your horse. Without water, there can be no mosquitoes. Empty all containers holding water except for the water your horse drinks. Wash out water troughs or buckets on a weekly basis. Mosquitofish, Gambusia affinis, can be added to your horse's trough to eat the mosquito larvae if they are legal in your location. Mosquito dunks, which contain Bacillus thuringiensis israelensis, can be put in water troughs or buckets to kill the mosquito larvae without hurting your horse.
All of the common mosquito borne illnesses, but especially West Nile Virus, normally live in birds. Venezuelan Equine Encephalitis lives in chipmunks or squirrels, but it is rarely found in the United States so far. Mosquitoes only bite horses when their primary host is not available when they need a meal. For that reason, discourage birds, especially crows and grackles, from nesting near your stable.. For some reasons, crows are especially susceptible to West Nile Virus and mosquitoes that bite them can spread it to your horse. Do not allow rodents such as squirrels or chipmunks to feed on the grain that the horse wastes. Try to keep wild animals and birds at a distance from your horse's living quarters.
Avoidance consists of keeping the horse in the stable at night, dawn, and dusk, when the mosquitoes are most active. All windows and doors that are open should have screens to keep the mosquitoes out of the stable. Outdoor lighting should be far enough from the stable that it does not attract mosquitoes. Finally, the use of repellants designed for horses is important. Do not use repellants designed for humans, as these may make your horse ill.
There are vaccinations for all of the equine encephalitis strains found in the United States and Canada. For West Nile Virus, two doses are given thirty days apart. The vaccination program should start approximately 3-6 weeks before the start of the mosquito season in your location. There are two vaccinations available. West Nile Innovator, made by Fort Dodge, has been shown in the lab to be 95% effective. It consists of killed components of the virus that trick the horse's immune system into producing antibodies against the virus. Recombitek Equine West Nile Virus Vaccine is a modified live virus vaccine. It uses the canary pox virus to carry proteins from the West Nile Virus and that causes the horse's immune system to make antibodies. Each year, the horse should be given a booster of the same kind of vaccine the horse originally received to make sure it stays healthy.
Vaccinations for Eastern, Western, and Venezuelan Equine Encephalitis are given in a similar fashion to the West Nile Virus vaccine. Your veterinarian will tell you which types of encephalitis are prevalent in your area and will administer the vaccinations for that type. Two vaccinations are required for each virus the first year, but there are products that contain vaccinations for all three of these encephalitis viruses. Consult your veterinarian to make sure your horse is properly vaccinated.
Follow the principles of reducing mosquitoes, avoiding mosquitoes, and vaccinating your horse to prevent mosquito borne illnesses. Such illnesses can prove deadly, making prevention essential.