I hear this line often: “Doc, my horse doesn’t need a Coggins! We don’t go anywhere!” I also occasionally hear: “Hey Doc, I need to get my horse that Coggins shot.” Other horse owners refuse Coggins testing because they believe there’s no way a horse would test positive; the Coggins disease has been eradicated right? How did this test come to be surrounded by so much confusion and so many misconceptions?
It’s interesting that, over the years, the Coggins test has developed a reputation as “health papers” or a “travel permit.” While it’s true that a Coggins is legally required to travel with horses (In North Carolina, every horse over the age of six months must have had a negative Coggins test result within 12 months in order to be sold or taken to any public place), I think we’ve lost sight of the real reason for this test!
A “Coggins” is a blood test that detects antibodies to the disease Equine Infectious Anemia (EIA). This is a virus that can cause affected horses (or donkeys) to have fevers, anemia (low red blood cell count), edema (stocking up), or weight loss/muscle wasting. Some horses recover quickly from the symptoms, which may be nothing more than a fever for <24 hours. EIA is a relative of the virus that causes HIV in humans. Horses that become infected will carry the disease 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 by flies (horse flies and deer flies), so your horse doesn’t actually have to come into contact with an infected or carrier horse to catch the virus. Flies come to your farm, so your horse is at risk even if he never travels, or lives in a closed herd. There is no vaccine for EIA and there is no treatment.
Another common misconception is that EIA has been eradicated from the United States, and that there’s no way a horse would test positive. In 2012, there were 36 horses identified as positive for EIA, 82 in 2011, and 49 in 2010. This disease remains active, at low levels, within the US horse population. Prior to introduction of routine testing, 3 in every 100 horses were positive for EIA. Since routine testing was introduced in 1973, the numbers have declined to 0.2% of horses testing positive. In the past, EIA was often transmitted from horse to horse through human intervention, with dirty needles or surgical instruments. Now that humans are more careful, the disease remains present due to biting flies. Since 1980, the majority of positive EIA horses were asymptomatic, so it’s incredibly important that we continue regular Coggins testing, to identify carriers and ensure that large outbreaks don’t take place.
What happens when a horse tests positive for EIA? After the result is verified, the law states that the horse’s owner has two choices- euthanasia or quarantine. If quarantine is chosen, the horse must be branded with a special “55A” and ID number on the left side of the neck. The horse must then be kept a minimum of 880 yards from any other horse for the rest of its life. Most people choose euthanasia.
So what’s with the name? Coggins? The test was was named after its developer, Dr. Leroy Coggins. Dr. Coggins was a veterinarian with a PhD in virology. He studied African Swine Fever in Kenya in the 1960s, and translated his findings to develop the test for Equine Infectious Anemia. The Coggins test was first approved by the USDA in 1973. Dr. Coggins lived in Cary North Carolina, until his death in Feb 2014 at the age of 81.
You probably hope that your neighbors are having their horses routinely tested for EIA, and they hope you are too! Is your horse’s Coggins current?