Equine Infectious Anemia (EIA) is an infection of the blood spread by biting insects such as mosquito’s and various biting flies. Pregnant mares that become infected are automatically assumed to have transmitted the disease to the foal and both mare and foal (once birthed) should be kept in isolation until the foal is weaned and can be tested. The foal should not be tested prior to weaning as it may give a false positive due to ingesting antibodies from the mare’s colostrum.
There are three “levels” of EIA;
- Symptoms appear within 1-4 weeks of first exposure
- Sudden fever, often reaching upwards of 105°F
- Rapid weight loss, anemia (in EIA the horse’s own white blood cells may attack its red blood cells) and hemorrhages of the mucous membranes
- Horse may have several bouts of fever, with normal periods in between
- Weight loss is more pronounced in this level since it is more due to its longer duration
- Horse may become depressed and stop eating altogether
- Anemia may be more severe
- Swelling of the legs and lower abdomen
- Horse may experience periods of fever, anemia and weight loss.
Any “level” of EIA can occur without any outward signs of the disease.
- There, unfortunately, is no effective treatment at this time.
- Once a horse contracts this virus it is impossible to eliminate it from the body. If the horse survives the virus it will be a carrier for as long as it lives.
- Fly and mosquito population control
- Sterilization of medical equipment (including dental equipment)
- Test all new horses (including new purchases and new boarders)
In my research for this article I found a few conflicting facts on the virus and so have included links to a few different sources for your own edification. My primary source for this article comes from the “Horseman’s Veterinary Encyclopedia, Revised and Updated” published by The Lyons Press in 2005. If you have any questions about this disease or suspect your horse may have come in contact with it, contact your veterinarian immediately.