27 July 2015
By Kathleen Winfield
You might have noticed that equine competitions and events are now beginning to request a negative result Coggins test as part of their requirements for entry in to the competition or event. If you frequently travel across international borders with equines, you already know that a negative Coggins is required: but do you know why? So – what is a Coggins test and what is it testing for?
A Coggins test is a blood test designed to determine if antibodies are present for the viral disease Equine Infectious Anemia (EIA). A negative result means no antibodies are detected. Blood samples are taken by an accredited veterinarian and the test performed in an accredited laboratory (accreditation by the Canadian Food Inspection Agency (CFIA)).
EIA is a persistent and incurable viral disease that attacks the equine immune system, including donkeys and mules. Symptoms of infected equines are highly variable and can resemble other diseases so diagnosis can be difficult without doing the blood test. Symptoms may include anorexia, fever, depression, small hemorrhages in mucous membranes, swelling of legs, lower chest and abdomen, fatigue, reduced stamina or weakness, rapid breathing and rapid weight loss, jaundice. An infected equine might only exhibit a loss of coordination. It is also possible that an equine may be a carrier of the disease but not show any symptoms. All horse owners should be aware of EIA, but not alarmed, as the prevalence has remained relatively low in western Canada.
This disease is transmitted by contaminated blood or blood products. Biting insects such as deer and horse flies are known transmitters of the disease. This transfer is strictly “mechanical” which means the virus does not replicate itself in the insect – it is contained in the blood from the infected equine that the insect carries on its mouthparts then deposits into the bloodstream of the next equine during the next bite. The virus only survives a short time on the insects so the disease is generally spread between horses in close proximity. As these insects thrive in wet areas, outbreaks of EIA have often been linked to horses pastured in swampy areas (thus the nickname of Swamp Fever for this disease).