Equine Infectious Anemia "Swamp Fever"

The state of Florida requires all horses to have a Coggins test annually to make sure the horse is free from the virus called Equine Infectious Anemia (EIA), also known as swamp fever. Last year 20 horses were found positive in the state of Florida.

EIA is a viral disease that attacks the horse’s immune system. It causes severe anemia by destroying the horse’s red blood cells, and can cause a high fever of 104-106 degrees, general weakness and chronic weight loss. Some infected horses show no signs and become chronic carriers of the disease. Since EIA is caused by a virus, there is no drug that will directly treat it. The only treatment is to give supportive therapy to bring down the fever and keep the horse comfortable.

The virus is spread by a species of fly called Tobanids, the large horse fly and deer fly are examples. Mosquitoes have not been shown to be able to spread this disease. The species of fly has large tearing mouth parts that will leave a visible drop of blood on a horse after biting him, making it possible to spread the disease by introducing contaminated blood to the next healthy horse he bites. Once infected, the horse may show signs of the disease one week to one month later. If tested positive the law requires the horse to be quarantined at least 200 yards away from any other horses, or if this is not possible, euthanasia is the only other choice to prevent the spread of this disease.

If purchasing a horse whose test was done more than four months ago, it may be wise to repeat the Coggins test, just to cover your bases. Never purchase a horse without proof of a current negative test.

By enforcing the law, the state Veterinarians are trying to eradicate a non-treatable disease that has no vaccine for prevention. This law can help the Florida horse population to remain healthy.

Richard Funk, D.V.M., Associate Veterinarian at Braden River Animal Hospital 5012 SR 64 East, Bradenton, FI 34208 (941)745-1513