Katie Hennessy

What Is a Coggins Test?

Most horse owners are familiar with the requirement for a negative Coggins test under various circumstances, such as traveling out of state, showing or selling your horse but many are not fully aware of exactly what is being checked. 


A coggins test is a simple blood test that screens for a blood-borne viral disease called Equine Infectious Anemia (EIA). The test looks for antibodies that will only be present in an animal that has contracted EIA at some point. 


A horse that shows symptoms of EIA may have a fever, depression, swelling on the ventral abdomen or legs or experience sudden weight loss. Although not every case of EIA is fatal, some horses will succumb and quickly die. While some horses get sick, others are asymptomatic, meaning it really doesn’t affect the animal. Once this virus enters an animal’s body, it never goes away. It can manifest its symptoms at any point in the horse’s life, as well as be transmitted to other horses or donkeys.


The EIA virus is spread between horses through contact with blood. This means that any biting insects such as horse or deer flies, which feed on blood, can transmit the disease from one horse to any others in the area. It also can be spread through the use of contaminated needles and syringes or through natural breeding. A pregnant mare can also pass the disease on to her foal in utero. 


Unfortunately, there is currently no cure or vaccine for EIA. An infected horse must be permanently quarantined or euthanized. The best preventive measures are proper health and sanitation protocols, including an integrated pest management system that utilizes multiple strategies to reduce the populations of biting flies. Always require proof of a negative Coggins test before purchasing, breeding or relocating any horses or donkeys.

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