Montana Horse Tests Positive for Equine Infectious Anemia (EIA)

by Fran Jurga | 27 April 2010 | The Jurga Report at

The testing of a single horse should not be cause for alarm, but it should serve as a reminder to all horse owners that it is important to have your horse tested routinely for EIA. Many of us only have a Coggins pulled on our horses if they are going out of state, and that means that older or stay-at-home horses don’t get tested, and often for years at a time, if ever. There are many things that are not known about this disease, which is currently a problem in the country of Romania in Eastern Europe and a concern to the transport of horses from that country to other European countries. This is a disease to be taken seriously. Ask your veterinarian about testing frequency guidelines for horses in your care and for risk factors in your region.

Officials in the Montana Department of Livestock (MDOL) announced yesterday that a horse has tested positive for Equine infectious anemia (EIA); this is the first case of the disease in that state since 2007.

The horse’s status was revealed following a positive result to a routine “Coggins” test.

Also known as swamp fever, EIA is a potentially fatal viral disease of horses spread by larger biting insects, like horse and deer flies, that feed on blood. No vaccine or treatment exists for the disease, which is characterized by intermittent fever, depression, progressive weakness, weight loss, edema (fluid under the skin or in body cavities) and anemia.

A Coggins test is a screening test required for the interstate movement of horses in the United States. The test was performed on this horse so it could be moved to another state and was positive. The result was confirmed by the USDA-APHIS National Veterinary Service Laboratories (NVSL) in Ames, Iowa.

A new sample has been drawn and submitted to NVSL, with results due early next week. Follow-up testing on two other horses located at the premise is also underway. Dr. Marty Zaluski, State Veterinarian for Montana, said the Department of Livestock has been on-site investigating how the horse became infected.

Owners of infected horses have few options. These include euthanasia or a lifetime quarantine with a minimum of 200 yards distance between the quarantined animal and other equines. Infected animals can also be used for research; some scientists believe such research would contribute to a better understanding of retroviruses such as EIA, AIDs (Acquired Immune Deficiency Syndrome) and Human immunodeficiency virus (HIV), as well as for developing an EIA vaccine.

Zaluski said the owner of the infected horse is currently considering these options and that testing of some neighboring horses will be required.

EIA is endemic to the Americas, parts of Europe, the Middle and Far East, Russia, and South Africa. Hot zones in the U.S have historically been located east of the Mississippi River, but the disease has been spreading west. The advent of testing has helped curb spread of the disease; the percentage of test-positive animals has dropped from nearly four percent in 1972 to less than 0.01 percent in 2005.

Although biting insects are the primary cause of infection, EIA can also be transmitted through contaminated surgical equipment, and from mares to foals via placenta. Some infected equines do not show typical signs of the disease, and serve as inapparent carriers of the disease.

Regular EIA testing should be included as part of a sound equine health management program, especially when horses have been in contact with animals of unknown EIA status. In addition, having horses tested prior to purchase is highly recommended. Best management practices for prevention include insect control, and making sure no common needles or instruments are used.

“As with all livestock diseases, working with your veterinarian is the best place to start,” Zaluski said. “This is especially the case for EIA, which can be difficult to differentiate from other fever-producing diseases like influenza and equine encephalitis.”

Equines that suffer weight loss accompanied by a periodic fever, or groups of horses that develop EIA-like symptoms after the introduction of a new horse into the herd, should be tested as soon as possible. Veterinary consultation should also be sought for any horse that dies of unknown causes.

EIA is a federally-reportable disease, although no USDA-APHIS eradication program exists because of its low incidence.

For additional information about EIA or testing requirements in the state of Montana, please contact MDOL’s Animal Health Division at 406 444 2043.

You may also wish to download the USDA Veterinary Services fact sheet on EIA.

Information from the Montana Department of Livestock was utilized in this blog post.Follow @FranJurga on for horse health news!




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