The Idaho State Department of Agriculture received confirmation of Equine Infectious Anemia diagnosed in a horse transported from Washington state back to its home in Canyon County in May.
EIA, an infectious and potentially fatal viral disease of horses, is most commonly transmitted by biting insects. Needles and other equipment contaminated with blood from an infected horse also can spread the virus to other horses.
Horses with the viral disease may develop a low-grade fever, become lethargic, lose weight, and demonstrate tissue yellowing, anemia, swelling in limbs and weakness.
Animals demonstrating clinical signs of EIA pose the greatest risk of spreading the virus, the department said in a release. But symptoms often are subtle, and can go unnoticed; these "inapparent carriers" can pose risk to other horses and cause infection.
The Coggins test is the most commonly used lab analysis for antibodies to EIA. All states require that horses have a negative Coggins result before they move between states.
ISDA State Veterinarian Bill Borton said he encourages horse owners to incorporate the test into their animal health regimens whether or not the animals will travel interstate.
“Horses that acquire EIA are infected throughout their lives and will remain a source of infection to other horses in close proximity, so Coggins tests are incredibly important to managing the spread of EIA,” he said in the release.
Idaho law has strict requirements for EIA-infected horses, including isolation from other horses for life, the department said.
No vaccine is available to prevent EIA, which does not pose a human health risk.