"This is a devastating disease," states Dr. R.D. Scoggins, equine Extension veterinarian at the University of Illinois College of Veterinary Medicine in Urbana. "There is no vaccine or effective treatment."
The virus can cause a high fever of 104-106 degrees and general weakness. It can also cause the horse to go off feed, have small hemorrhages in the mouth and at the base of the tongue. Other signs may be paleness of the mucous membranes and swelling of the legs and the ventral midline. This disease can also cause chronic weight loss. There is also a significant decrease in the horse's performance level.
EIA can be passed from horse to horse by mosquitoes and biting flies, especially horse flies. Needles contaminated with infected blood are also a source of infection. Once infected, the horse may show signs of the disease one week to one month later. Some infected horses show no signs and become chronic carriers of the disease. Carrier horses that become stressed will often show signs of the disease.
Since EIA is caused by a virus, there is no drug that will directly treat it. About the only thing veterinarians and owners can do is give supportive therapy to bring down the fever and keep the horse comfortable. Most infected horses are euthanized because they will shed the virus during periods of high fever. If the owner chooses to keep an infected horse, the animal must be kept in strict isolation, including insect-proof screening to avoid transmission to other horses.
In Illinois, a negative Coggins test is required for animals going to advertised events--sales, shows, parades, rodeos and travel across state lines. The Illinois Department of Agriculture is responsible for checking Coggins tests. However, show managers and farm owners may require proof of a negative Coggins test before they allow horses onto their premises.
"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," advises Dr. Scoggins. "Never purchase a horse without proof of a current negative test."
Since the state requires a negative Coggins test for any horse over one year old that is presented for public auction, those that go to sales without proper proof can only be sold for slaughter. If an owner is not aware of these new laws, and hasn't had the horse tested, the horse can be withdrawn from the sale and taken home. Once sold, the horse can not be withdrawn. Sale barns may insist that only horses with negative tests can be sold.
Any untested horse will be tested by the state for purpose of traceback. This allows the state to keep track of positive horses and help protect other horses in the area. When a positive horse is found, the state will pay for testing any horse within a three-mile radius of the positive horse. The testing will be done by state veterinarians.
A Coggins test is very simple for the horse and the owner. A licensed, federally-accredited veterinarian must draw blood from the horse. A form is filled out at the farm identifying the horse by age, breed, sex and color markings. Registration numbers and breed registry names are also included if relative. Then the form and the blood are sent to the state lab to be processed.
By introducing these new laws, the state veterinarians are trying to eradicate a non-treatable disease that has no vaccine for prevention. These changes can protect the Illinois horse population.
If you have any questions about EIA or the Coggins test, contact Dr. Richard Hull, State Veterinarian, Illinois Department of Agriculture in Springfield, 217/782-4944.
Source: April 22, 1996 Horse Column, UI CEPS/Extension, Written by Linda March, Fourth-Year Veterinary Student, University of Illinois, College of Veterinary Medicine.