Indiana Horse Owners Warned of Infectious Anemia Risk

Horse owners and veterinarians are being asked to watch their animals closely for any unusual clinical signs, in light of a cluster of recent positive cases of equine infectious anemia (EIA).

According to Tim Bartlett, DVM, director of equine programs for the Indiana State Board of Animal Health, three horses on a south-central Indiana farm have tested positive for the disease in the last few weeks.

State and federal veterinarians have been working with the owner to identify the source of infection and determine if any other animals are at risk. All three positive horses have been euthanized; two herdmates have tested negative and remain under quarantine until further testing is complete.

EIA, also known as swamp fever, is an untreatable and incurable viral disease that infects horses, ponies, donkeys, mules, and other equine.

Depending on an individual horse's immune system and the severity of its reaction, clinical signs of EIA can range from virtually none at all (except a positive blood test) to weakness, weight loss and swelling to fever, rejection of feed, and sudden death.

A blood test (often called a Coggins' test), conducted by a veterinarian, can detect the infection. However, equine owners should remember that test results can produce a false negative up to 42 days after exposure to the disease, before a detectable level of antibodies develops.

What can horse owners do to prevent EIA?

Bartlett said the disease is spread via blood-to-blood transmission, not close proximity or casual contact. "Blood transfusions, unsterilized or contaminated needles and medial instruments can transmit the virus," he said. "But horse owners should be most concerned about biting insects--especially horseflies--which can spread the disease."

He also advised equine owners use specific management strategies to minimize the chance of EIA entering their herds via new animals.

"All equine should be tested for EIA before being brought onto a farm," Bartlett said. "Then, the animal should be isolated and observed for 45 days to 60 days, then retested before it is introduced to the herd."

State law requires all equine entering Indiana have a health certificate indicating a negative EIA test within the previous 12 months. Suckling foals, accompanied by an EIA-negative dam, are exempt from testing.

In Indiana, once a horse (or other equine) tests positive for the disease, the animal must be permanently identified with "32A" freeze-branded on the left side of the neck to comply with state law. Permanent identification is designed to protect Indiana's healthy equine population, by eliminating confusion about health status.

The owner then has two options for handling the horse: 1) Permanently quarantine the animal to the owner's premises, at least 200 yards from the nearest equine; or 2) Euthanasia (at the owner's expense) after notifying the state veterinarian. All other animals in the herd must also be tested for EIA.

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