What is coggins or EIA?

I am the first person to admit that I don't know everything. So when I heard some staff at the barn talking about a coggins test, I thought to myself "what the heck is coggins?" I've never owned my own horse nor have I ever purchased one, so the massive amount of details, research and planning that goes into such a purchase are a little unfamiliar to me.

After a little snooping around I discovered coggins is actually the name of a test and a person. "The Coggins test (agar immunodiffusion) is a sensitive diagnostic test for equine infectious anemia developed by Dr. Leroy Coggins in the 1970s.” (1) The test actually looks for antibodies developed to fight the disease. (2)

This of course led to my next questions, what is equine infectious anemia? "Equine Infectious Anemia (EIA) is a viral disease for which there is no vaccine and no cure. Though most horses succumb rapidly to EIA a percentage of infected horses appear to recover. However they still harbor the virus and during times of stress may become ill again." (3) There is a vaccine that has been developed in China (2), but to the best of my research I was unable to find any information about its availability in the United States. Similar to HIV, EIA is lentivirus. Also similar is that EIA, like HIV, can be transmitted through blood, saliva, milk, and body secretions. Biting insects tends to be the most common means of transmission. (1) According to J. Warren Evans in his book Horses, 3rd Ed. "The disease affects less than 1 percent of the horse population.”(4)

There are three stages or sets of symptoms of EIA:
Acute: " The acute form is a sudden onset of the disease at full-force. Symptoms include high fever, anemia, weakness, swelling of the lower abdomen and legs, weak pulse, and irregular heartbeat. The horse may die suddenly."(1) "With acute infection the horse also has depression and no appetite. The acute horse may be difficult to diagnose because the symptoms are very general and he will not be positive on the EIA test for a month and a half. Approximately one third of infected horses will die of the acute form within a month."(3)

Subacute: "A slower, less severe progression of the disease. Symptoms include recurrent fever, weight loss, an enlarged spleen, anemia, and swelling of the lower chest, abdominal wall, penile sheath, scrotum, and legs."(1) “Subacute forms are less severe, so the horse survives.” (4)

Chronic: "Horse tires easily and is unsuitable for work. May have a recurrent fever and anemia, may relapse to the subacute or acute form even several years after the original attack." (1) "The chronically infected horse will having recurring acute bouts along with weight loss, ventral edema (swollen belly and legs) and anemia. These horses will be positive on a EIA test. These horses may linger for a year or more before they die." (3)

So what happens to a horse that has EIA? J. Warren Evans sums it up as follows:

“The temperature of an acutely infected animal rises to 105 to 108°F. The horse appears depressed, becomes weak, and loses appetite and weight. Fluid (edema) may collect under the skin, in the legs, chest and abdomen. Membranes lining the natural body openings may be congested and yellow in color. There is a marked drop in the number of red blood cells (anemia). The horse usually dies in a few days.” (4)

What did I learn from my little educational and inquisitive foray into the mystery that is "The Coggins Test"? Buying a horse is a HUGE decision and you should spend at least as much time researching and riding a potential new purchase as you would researching and test driving a car. The more time and research you invest the more likely you are to be satisfied with your equine purchase and well on the way to being a happy horse owner.

End Notes:

(1) : http://en.wikipedia.org/wiki/Equine_infectious_anemia

(2) Evans, J. Warren. Horses, 3rd Edition: A Guide to Selection, Care, and Enjoyment. Holt Paperbacks, New York, NY. 2001. Page 383.

(3): http://www.eqgroup.com/Library/coggins.htm

(4) Evans, J. Warren. Horses, 3rd Edition: A Guide to Selection, Care, and Enjoyment. Holt Paperbacks, New York, NY. 2001. Page 382.