For starters, Coggins is a test not a disease. The Coggins Test is a diagnostic tool to analyze a horse’s blood for the presence of antibodies to Equine Infectious Anemia Virus (EIAV). Blood is drawn by an accredited veterinarian and submitted with paperwork, indicating the horse’s markings and current location, to an approved lab for testing with the Coggins Test. This test is required by all states to cross the border with only a few exceptions. Some states also require it for change of ownership, trail riding, and shows. Once tested, the paperwork is only good for a year, or less in some states, so the horse must be retested.
What is it?
EIAV, also known as Swamp Fever, is a retrovirus virus that makes its own DNA. This DNA is incorporated into the genetic material of the horse’s infected cells. First diagnosed in the US in 1888, it causes 3 different clinical presentations, an acute form, a chronic form and an inapparent form.
The acute form is the most devastating and difficult to diagnose of the presentations. When exposed, the horses can become gravely ill and die within 2 to 3 weeks; sometimes, the only sign being a fever short after exposure. Many times, this fever is gone long before the horse is examined by a veterinarian. This stage is the most dangerous to other horses as 1/5th of a teaspoon of blood from an acute form horse can infect over a million horses.
If the horse recovers from the acute form, it can continue into one of two other forms. In the chronic form, the horse has recurring problems including high fevers, anemia, weight loss, and depression. The anemia also causes small blood spots in the mucus membranes called petechial hemorrhages and edema in the lower legs and under the belly and chest.
The 3rd is the inapparent form, and is the most common form detected in horses. No signs of disease are shown by these horses and are usually only found with routine annual testing. In this form, the virus load is extremely low, yet, it is the most common source of the virus for other horses. The infection is for life and can change forms if the horse is stressed or becomes ill from a second disease.
How is It Spread?
EIA is spread by blood transfer. So things such as biting insects and blood contaminated
needles are the main sources for the transmission of this virus. Biting flies spread the virus
by first biting the infected horse and mid feeding the fly gets interrupted. Disruption makes
the fly more aggressive and it immediately flies back to continue feeding, sometimes on a different uninfected horse. The blood on the mouth of the fly transfers to the second horse. This is the most common form of transmission, however, it is highly dependent on the amount of virus present, the amount of flies present, the number of horses and the current
weather, so don’t panic if your horse gets bitten at a horse show! The virus can be transmitted by mares to their foals before birth and through her milk, as well as from a stallion to a mare while breeding; however, these transmissions are not consistent.
Is There a Treatment?
There is no treatment or vaccine for the virus and the horse is infected for life. Once the
first test is positive, the horse and all horses that were within 200 yards will be put into
quarantine. After the confirmation of the positive test, the horse will be removed from the other horses and placed into its own permanent isolation screened area or transported directly to slaughter or an approved federal lab. The isolated horse can also be euthanized at the location. The remaining horses must be tested at 30 and 60 days and the quarantine will be lifted if all remaining horses are negative at the last test.
How common is the virus?
Number of Tests Performed in the US in 2017: 1,299,683 (0.006% positive in 2017 for all of US)
What you Need to Remember!
- Coggins is a test, not a disease. Equine Infectious Anemia Virus is the disease it tests for
- Always have a current Coggins Test when crossing states lines and check with your vet for other requirements
- Though not common, EIAV is still a deadly, contagious disease
- EIAV is a lifelong, incurable blood- borne disease spread by biting flies and dirty needles
UPDATE: As of April 16, 2018, there are 2 confirmed cases of Equine Infectious Anemia in Iowa. Both cases were located on the same premises in Polk County and have been euthanized.