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Care Guide

About Care Guides[x] These care guides are written to help your clients understand common conditions, tests, and procedures, as well as to provide basic information about pet care. They are based on the most up-to-date, documented information, recommendations, and guidelines available in the United States at the time of writing. Pharmaceutical product licensing, availability, and usage recommendations are based on US product information. Use the Download Handout button to generate a PDF for printing or e-mailing to your clients.

Coggins Tests

    • The Coggins test is used to detect equine infectious anemia (EIA)—a highly contagious and potentially fatal viral disease of horses.
    • EIA is regulated by the United States Department of Agriculture, but state laws vary regarding testing. A current, negative Coggins test result is often required to transport horses across state lines.
    • Horses that attend equine events are usually required to show a current, negative test result to participate.
    • The EIA virus is transmitted through insect bites and through contact with infected body fluids.

    What Is It?

    In the 1970s, Veterinarian Leroy Coggins developed the test that bears his name. The Coggins test detects equine infectious anemia (EIA)—a potentially fatal viral disease of horses. With no vaccine available, the only way to prevent the spread of this highly contagious disease is by taking physical precautions. EIA is most often spread through insect bites, primarily horseflies. It can also be transmitted through saliva and other bodily secretions, blood, and shared syringes and bridle bits. Infected pregnant mares can pass the virus to their foals. While the United States Department of Agriculture (USDA) estimates that fewer than eight in 100,000 horses become infected with EIA, 50% do not survive despite treatment.

    EIA comes in three forms: acute, chronic, and the inapparent carrier. In the acute form, horses experience fever, lethargy, and loss of appetite, and many die within a few weeks even if they receive aggressive treatment. If they recover, they become chronic carriers and are contagious for life. Chronically infected horses become ill, recover, and then become sick again and never completely recover. They often lose weight and suffer from anemia and swollen limbs. Horses that are inapparent carriers appear healthy but can spread the disease to other horses, eventually becoming ill themselves.

    How Is It Performed?

    To perform a Coggins test, your veterinarian will take a blood sample and identify your horse on the form by a drawing or picture. The blood sample and form will be sent to a USDA-accredited laboratory for testing. The Coggins test looks for the presence of antibodies specific for the EIA virus, which an infected horse produces after exposure to the virus. Antibodies are proteins produced by the immune system to fight infectious diseases due to organisms such as bacteria or viruses. Lack of these specific antibodies in the blood produces a negative Coggins test result. The test is about 95% accurate; however, if the test result is positive, your veterinarian will send supplemental tests to confirm the results.

    Why Is It Used?

    The Coggins test is performed to identify infected horses and prevent the disease from spreading to healthy horses. In the United States, there are certain high-risk regions and states, such as Texas and Oklahoma; however, sporadic outbreaks can occur also. Therefore, horse owners should have Coggins tests performed annually, test all new horses arriving on their farm, and use proper fly control. Horse owners are usually required to submit a current, negative Coggins test result when they attend horse events. A current, negative Coggins test result is often required to transport horses across state lines. Most stables require new boarders to provide a negative test result. In addition to testing, never reuse hypodermic needles or share equipment, such as bits and surgical materials, because contact with infected body fluids spreads the disease between horses.

    Reviewed January 2012