On Thursday August 28, the Montana Department of Livestock (MDOL) received notification that a horse from Musselshell County had tested positive for Equine Infectious Anemia (EIA). The property where the animal is housed is under quarantine and follow-up testing on the animal is underway.
The infected horse was discovered when it tested positive on a screening test required for equids to move across state lines. Commonly known as a Coggins test, the preliminary positive result was confirmed by the USDA-APHIS National Veterinary Service Laboratories (NVSL) in Ames, Iowa.
MDOL will investigate the movement and ownership history for the infected animal to identify other horses that may have been exposed to the disease. Exposed animals will be tested to verify disease status.
EIA is a potentially fatal viral disease of equids (horses, ponies, zebras, mules, and donkeys) transmitted on the mouthparts of certain biting and blood sucking insects. The disease can also be spread through contaminated needles or other equipment that may move blood between horses (iatrogenic transmission). No vaccine or treatment is available for the disease, which is characterized by fever, depression, progressive weakness, weight loss, edema (fluid under the skin or in body cavities) and anemia. Not all horses will show signs of illness and can serve as carriers capable of spreading the disease.
“Cases of EIA in Montana are sporadic and unfortunately, we are not always able to identify the original source of infection,” said Tahnee Szymanski, Montana State Veterinarian. “The best protection from this disease is to test new purchases along with required testing for interstate movement.”
Due to strict regulations and no available treatment, there are limited options for the management of infected horses. Infected horses can be placed under a lifetime quarantine with a minimum of 200 yards distance between the quarantined animal and other equines, euthanized, or donated for EIA-related research.
While the incidence of EIA has decreased since Coggins testing began in 1972, the United States still sees 100+ cases annually. Cases of EIA are most often found in one of several high-risk populations including Quarter Horse racehorses with iatrogenic transmission, horses illegally moved from Mexico where the disease is endemic, and in untested or undertested herds. Montana’s last positive detection of EIA was in 2017.
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MDOL
