According to the Montana Department of Livestock (MDOL), Equine Infectious Anemia (EIA) has been diagnosed in several horses on a Gallatin County premises.
The premises is currently under quarantine with the remaining horses undergoing follow-up testing.
The MDOL stated the infected animals were discovered when they tested positive to a screening test required for equine movement into or out of the state.
Preliminary results of the screening test, also known as a Coggins test, were confirmed by the USDA-APHIS National Veterinary Service Laboratories (NVSL) in Ames, Iowa.
MDOL has additionally contacted all horse owners within 200 yards of the affected herd regarding potential exposure and testing requirements.
Also known as swamp fever, EIA is a potentially fatal viral disease of equines spread by biting insects. 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.
Although not all horses show signs of illness, infected animals serve as carriers capable of transmitting the disease.
Due to strict regulations and no available treatment, owners of EIA-infected equines have few options. Infected horses can be placed under a lifetime quarantine with a minimum of 200 yards distance between the quarantined animal and other equines, euthanasia, or donating the animal for EIA-related research.
The incidence of EIA has decreased since Coggins testing began in 1972, with approximately 50 cases of EIA diagnosed in the United States annually. Pockets of the disease continue to be found in populations with limited interstate movement, which are rarely tested.
EIA was last diagnosed in Montana in 2011 in Carbon County.
For additional information about EIA or testing requirements, please contact MDOL's Animal Health Division at (406) 444-2043. Additional information is also available at:
For more information on the Montana Department of Livestock, click here.