Horse owners should watch horses, mules, donkeys and other equids closely for any unusual disease symptoms, in light of a cluster of recent positive cases of equine infectious anemia (EIA).
According to Dr. Tim Bartlett, a veterinarian and director of Equine 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 positives have been euthanized; two herd mates have tested negative and remain under quarantine until further testing is complete.
EIA, also known as swamp fever, mountain fever or malarial fever, is an untreatable and incurable viral disease that infects horses, ponies, donkeys, mules and other equine. An estimated 30 percent to 50 percent of infected equine die within two weeks to four weeks of the onset of EIA.
Depending on an individual horse’s immune system and the severity of its reaction, EIA symptoms 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 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? Dr. Bartlett explains the disease is spread via blood-to-blood transmission, not close proximity or casual contact. “Blood transfusions, unsterilized or contaminated needles and medical instruments can transmit the virus,” he says. “But horse owners should be most concerned about biting insects–especially horseflies-which can spread the disease.
“Research shows that as few as three horseflies can carry enough virus from one animal to another to cause an infection. That’s why pest control is critical to the control of this disease,” adds Dr. Bartlett.
He also advises equine owners to minimize the chances of EIA entering their herds through newly purchased animals. “All equine should be tested for EIA before being brought onto a farm,” Dr. Bartlett says. “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.
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 herdmust also be tested for EIA.
Anyone wanting more information about EIA may contact his/her local veterinarian. Information about EIA is available online at the Indiana State Board of Animal Health .
(Press release provided by US Eventing Association)