Equine infectious anemia has been a horse owner's worst nightmare for many years, but thanks to new federal, state and provincial government testing requirements this condition is not nearly as devastating as it was just 20 years ago in North America. Equine infectious anemia is what the Coggin's Test is designed to identify. This simple blood test is the best and easiest way for a horse owner to ensure that his or her horse is safe both for their own peace of mind as well as to let others know that the horse is free from the condition.
A vet must do the Coggin's Test, which simply includes a small blood sample that is drawn from the horse then sent to a government approved testing lab. Once a negative result is obtained, the horse is considered to be free from equine infectious anemia and can usually be moved across state lines, boarded or stabled as well as entered into events and competitions. Horses with positive results cannot and must be kept under very controlled situations to prevent the spread of the disease.
The reason that equine infectious anemia is so problematic is that there is no cure for the condition, nor is there any vaccine against the condition. It is now understood that equine infectious anemia is passed from horse to horse through the bite of the large horsefly, however the virus is rather fragile and can only live in the horsefly about 20 minutes. This means that the horsefly, in order to transmit the virus, must bite the infected horse, then, within 20 minutes or less, bite another horse, thereby transmitting the virus.
Horses, once infected can respond in one of three ways. About one third of all horses infected with equine infectious anemia will develop acute symptoms and will die within one month. These symptoms will include loss of appetite and energy, weight loss and extreme despondency. This condition can mimic many other conditions and is made even more difficult to diagnosis because the Coggin's Test will not usually test positive until a month and a half after the horse was infected.
Chronic equine infectious anemia will result in the horse going through periods of showing the same signs as an acute horse, just not to the same degree. Often these horses will appear very pot bellied and have swollen legs as well as the typical signs of anemia including poor color of the gums and mucous membranes. A chronic case of infectious anemia will usually result in death of the horse within one year to eighteen months of development of the conditions.
A third type of infection results in a horse that is an asymptomatic carrier, or a horse that shows no signs of the disease but still tests positive on the Coggin's Test is possible as well. These horses are the most problematic as, unless the owner tests, will never be identified as carriers but will put other horses in the area at risk.
The only way to protect your horse is to use regular fly repellent throughout the season, ensure that they are only pastured or stabled with horses that test negative, and immediately remove any sick horses from the pasture to prevent possible spreading of the condition should it be diagnosed.