Most horse owners have heard of the Coggins test, but do not necessarily know what it tests for, or the implications of the test results. A “Coggins” is a blood test that detects antibodies to the Equine Infectious Anemia (EIA) virus, also known as swamp fever.
This virus can cause affected horses (and other equines such as donkeys and mules) to have fevers, anemia (low red blood cell count), general weakness, jaundice, petechia (small pinpoint hemorrhages) of the gums, edema (stocking up), or weight loss and muscle wasting. In some cases it can be a fatal infection. Many horses recover quickly from the symptoms, which may be nothing more than a mild fever. Horses that become infected will carry the virus for life. These carriers often show no signs of disease and appear healthy. Carriers then serve as a source of disease transmission to other horses.
EIA is transmitted mainly by biting flies (horse flies, deer flies and stable flies) that take a blood meal from an infected animal and then move on to another animal to feed, passing the virus into their bloodstream. Transmission can also occur if using needles or other blood-contaminated items on multiple horses. It is also possible for a foal to become infected in utero from an infected mare. There is no vaccine for EIA and there is no treatment. EIA is a reportable disease, which means that animal owners, veterinarians and laboratories are required to immediately report the presence of an animal that is infected or suspected of being infected to a CFIA (Canadian Food Inspection Agency) district veterinarian.
A negative test result is required to cross an international border. Many barns, shows and other equine events also require a negative Coggins test prior to the animal arriving at the property or facility. Testing prior to purchasing a new horse is also recommended. If a horse tests positive for EIA, the CFIA will step in and that animal and any in contact animals will be quarantined. The test results will be confirmed, and all equines on the premises or that have been in recent contact with the affected horse will also be tested. Horses confirmed to be infected with EIA must either be euthanized or placed under permanent quarantine in a fly-proof facility where possible.
The best way to protect your horses is prevention. Horses in close proximity to infected animals are most at risk as the virus does not survive long on the insects. Ideally horses that are leaving your property and commingling with other horses should be tested annually. Any new horses should have a negative Coggins test prior to arriving on the property. New horses should also be quarantined for 45 days to monitor for signs of illness. Use single use needles and syringes for vaccines or medications. Control biting flies by using insecticides/repellants appropriately, minimize breeding sites with manure management and by providing adequate drainage for water. Luckily, the incidence of EIA is quite low in the Peace Region.
Dr. Kim Jones joined the North Peace Veterinary Clinic care team in 2009 after graduating with distinction from the Western College of Veterinary Medicine. Originally from Kelowna BC, Dr. Jones is an active member of the Fort St. John Community and enjoys life in northern BC.