from the Vet Corner Archives

Part of Horse Previews Magazine website. Posted on 5/7/98; 2:00:00PM.

Veterinary Corner 5/98: Do I really need a Coggins Test, Doc?

by Frosty Franklin, DVM
Edgecliff Equine Hospital
S. 1322 Park Road, Spokane, WA 99212 * 509/924-6069

I'm going to Montana for a pack trip and my horse isn't sick. Do I really need a Coggins test, Doc? The answer to the previous question is an emphatic and resounding yes. With warmer weather and show season upon us, interstate travel requirements, one of which is a negative Coggins Test, become very important. Many horse owners are familiar with Coggins testing, but are unfamiliar with the disease the test detects. In order to better understand why Coggins testing is so important, let's examine the disease, equine infectious anemia (EIA).

EIA is a viral disease that affects the horse's immune system and other organ systems. It is a blood borne disease and is usually transmitted from horse to horse via biting insects like horse and deer flies and mosquitoes. People can also spread the disease by using contaminated equipment on more than one horse (i.e. using a single needle on multiple horses). Also called Swamp Fever, EIA has a higher incidence in states like Texas, Florida, and Mississippi that have warm, wet regions. However, EIA can occur wherever there is a vector to transmit it.

Signs and symptoms can include any of the following: fever, depression, decreased appetite, fatigue or reduced stamina, rapid breathing, sweating, rapid weight loss, bloodshot eyes with watery discharge, swelling of the legs, lower chest, and abdomen, weakness characterized by wobbly or rolling gait, pale or yellowish mucous membranes, irregular heartbeat and/or weak pulse, colic, and abortion in mares. This list of signs and symptoms is extensive, however, horses infected with EIA may not show any of them.

Horses infected with EIA can be in any of three stages: active, chronic, or carrier-only. The active state is characterized by active virus replication which causes damage to immune and other organ systems. Clinical signs are apparent during this stage.

The chronic state includes bouts of virus activity during which clinical signs present combined with times of remission, or an absence of clinical signs. In the carrier-only state, the horse has an absence of clinical signs, but can still infect other horses. Because the range of signs and symptoms vary so much from horse to horse, EIA is often difficult to diagnose, thus it is critical to have your horse tested for the disease at least once a year. Your horse should be tested more often if it is in a public stable which has a steady influx of new horses or if the horse travels frequently.

Once infected, a horse becomes a life long carrier of the disease. Because EIA has no effective treatment, or cure and there is no vaccine to prevent it, only 2 options exist for horses who test positive for the disease: lifelong quarantine in a screened stall or euthanasia. Federal and state agencies, as well as the American Association of Equine Practitioners, support euthanasia as the most prudent option.

As you can see, a diagnosis of EIA is a serious problem for both the horse and horse owner. Coggins testing ensures that any carriers of the virus are removed from the general horse population, thus lowering the incidence of the disease. Strict Coggins requirements were not put in place to make interstate travel, etc. more difficult. Rather, these requirements protect your horse and allow you peace of mind. Not only do you know your horse tests negative for the disease, but you also know that other horses your horse may come into contact with have also tested negative.


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