UNIVERSITY PARK, Pa. -- Equine infectious anemia (EIA), an incurable infectious viral disease of horses, has been identified as the disease affecting 21 horses in Pennsylvania's Wayne County. A veterinarian in Penn State's College of Agricultural Sciences urges all horse owners and horse boarders to test their stock for this disease.

"This disease has been with us a long time," says David Griswold, research associate in veterinary science. "Infected horses are detected in Pennsylvania every year, but seldom in such a concentrated grouping."

The outbreak originated at two Wayne County farms that provide riding horses for various summer camps in the area. Eighteen of the 21 horses in those herds that tested positive for the disease have been destroyed. Three other horses are quarantined. However, not all the horses that may have been exposed to EIA have been accounted for.

Horses infected by EIA can be identified by using the Coggins test, a blood test that identifies the antibodies that form to fight the virus. Those that test positive can be euthanized or quarantined. "A quarantined horse must be held in a screened-in pen at least 200 yards away from other horses," Griswold explains.

"It takes from two weeks to a month from the time the horse is infected to form enough antibodies to give a positive test result, so owners may have to test more than once if a horse shows any symptoms," Griswold says.

Symptoms of the disease are:

--Depression. The horse may seem lethargic and not eat well. --High fever. --The mucus membranes may turn yellow. --At times there may be swelling in the legs and brisket.

About a third of the horses with the disease will die within a month of infection. Another third will experience chronic symptoms off and on, and can linger up to one year before dying. Some horses will show no symptoms at all, which makes testing all the more important, Griswold says.

The disease is transmitted by blood transfer from one horse to another. "Biting insects, particularly horseflies and mosquitoes, are the main vector of the infection," Griswold says. "The prime time for infection is in the warmer months when insect activity is common."

Griswold lists some management tips for horse owners:

--Before buying any horse, insist on a negative Coggins test result within the last 30 days. --Diligently remove manure and use insect repellents to control flies. --Use individual water and feed buckets. --Use individual tack, which means saddles, bridles and bits. --Do not share grooming equipment. --Do not use dental instruments, hoof knives or hoof picks on more than one horse. --Hypodermic needles should be used for single injections, then destroyed.

"If you are considering buying a horse through auction or from an individual, insist on a pre-purchase test and try to find out the history of the animal," Griswold says. "If the owners are not willing to divulge that, look elsewhere."

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EDITORS: To contact David Griswold, please call 814-863-8526.

Contacts: John Wall jtw3@psu.edu 814-863-2719 814-865-1068 fax