What is Coggin's Disease?

by Barbara Power

Someone asked me once, What is Coggins disease? I knew just enough to tell them that Coggins was not an illness, but a blood test for an incurable disease known as Equine Infectious Anemia. Beyond that my well of wisdom ran dry.

Equine Infectious Anemia, however, is a serious enough threat to the equine population that all persons remotely interested in livestock should acquaint themselves with the particulars of the disease and the laws that have been enacted in an effort to control it.

EIA, also known as swamp fever or malarial fever because of its concentration in warm, humid climates, is an incurable viral infection spread by blood-to-blood contact. While it is usually transmitted by biting flies and mosquitoes; contaminated medical instruments and needles can also transmit the disease. Despite extensive research, there is no cure, vaccine, or effective treatment.

Preventive methods include sterilizing all medical equipment particularly tattooing needles and dental equipment, using disposable needles only once (and then disposing of them appropriately), and fly control. Horseflies are especially potent carriers because of the amount of blood they can transport. In areas where the virus is prevalent, cleaning and sterilizing brushes, combs, and farrier equipment is also recommended.

Symptoms of the virus may appear in one of three forms: acute, chronic, or inapparent (asymptomatic). The acutely affected animal will suffer from fever, dramatic weight loss, marked anemia, signs of jaundice, stiffness, weakness, depression, and occasionally edema or swelling around the lower abdomen, chest, and legs. Pulse and respiratory rates will be high and the animal may die. Animals that recover from the initial attack are infected for life and often develop the chronic form, in which symptoms reoccur, especially during times of stress, work, travel, or illness. Some animals, known as inapparent carriers are infected but never show signs of illness. However these animals are contagious and a major source of infection in healthy animals.

EIA has an incubation period of one to three weeks, but may take as long as three months before symptoms become noticeable. Infected mares can pass the virus to their foals during gestation or lactation. If the mare is an inapparent carrier, the foal may not contract the disease, although it will test positive until it is about six months old. Foals that test negative at seven months are considered free of the virus.

Animals are tested for EIA via a blood test developed by Dr. Leroy Coggins of New York State Veterinarian College, Cornell University. The test, in technological jargon, is the agar gel immunodiffusion or AGID test, and is considered valid only if the blood sample is drawn by a veterinarian and tested at an approved laboratory. The results are based on detection of antibodies to the EIA virus. Infected animals become positive for testing two to four weeks after onset of the initial infection and will test positive for the rest of their lives.

Animals that test positive are brought under the jurisdiction of the local state Animal Health Commission, which, depending upon that states laws, can offer several options for the disposal of the animal, none of which are desirable. Owners of horses with EIA may be offered the option to:

1. keep the infected animal under permanent quarantine away from all other equine. Regular testing may be required.

2. send the animal to slaughter or to an approved research facility

3. have the animal humanely euthanized.

Because of the strong emotional attachment people have for horses, legislation on EIA has met with much discord. Most states require that all equine being sold, transported, or participating in any public event must have a negative Coggins test with 12 months period. Many equine owners fail to understand the reason for this testing, especially in areas where the virus is not prevalent. Still others are unfamiliar with the nature of the disease and the disastrous effects it has on both the horse and its owner.
For equine owners in heavily infested areas, such testing is more commonplace and more readily understood and accepted.

The subtle and deadly nature of the virus makes testing a necessity in order to control the disease. According to Gary Fambro, DVM of Breckenridge, Texas, the reason to test is to protect the horse industry. A $10,000 horse becomes a $500 piece of meat if it tests positive and this has happened in the race horse industry. He adds that, testing is being a good neighbor. Because of the way the disease is spread, I would not want my horse that is negative around anyones horse that is unknown.

Discovering that a seemingly healthy horse is a carrier of a deadly, contagious disease is a tragedy no horse owner wants to face. Watching a favorite riding mount and partner suffer or die from that same disease is no better option. EIA is a very real threat to the horses, mules, and donkeys that people love and work with everyday. The only cure is to eradicate the virus before it can spread and the only way to detect the virus is the have the animal tested. Testing for EIA protects horse owners, their neighbors, and their four-legged friends.