The Coggins Test is a blood test that tests for Equine Infectious Anemia (EIA).
EIA, also called Swamp Fever, is a virus that circulates in the blood of horses and other equids.
It is primarily transmitted via biting flies such as the horse fly, deer fly, or stable fly. The labium of biting flies can suck blood from an infected horse, then move to a different horse and deposit blood from the first horse which can transmit disease to an uninfected horse. Other ways EIA can be transmitted are through blood-contaminated needles, transmission from an infected mare to her foal in utero, and by infected semen.
EIA is not a common disease however horses with EIA remain infected for life and are lifelong carriers. All infected horses can shed the virus although those with clinical signs or higher viral loads (higher circulating virus) are more likely to spread the disease. In severe cases, horses will die from infection with EIA.
Clinical signs include, but are not limited to, fever, depression, anemia, and weakness.
A diagnosis is made through blood testing with the Agar Gel Immunodiffusion (AGID) test and the Enzyme-Linked Immunoassay (ELISA) test which tests for antibodies in the blood. There is no treatment or cure for EIA. Infected horses must be quarantined for life. Most are euthanized. There is no available vaccine, though keeping fly levels low can help with prevention.