The Idaho State Department of Agriculture’s Division of Animal Industries has reported a positive case of Equine Infectious Anemia (EIA). On November 28, 2016, the National Veterinary Services Laboratory confirmed a positive case of EIA in a horse located in Canyon County, Idaho. The premises and all horses within 200 yards surrounding the premises are currently under quarantine until further testing of exposed horses is complete. The affected horse was part of a group that underwent testing in preparation for interstate travel. Exposed horses will remain under quarantine until follow-up testing is completed at 60 days post exposure. An epidemiological investigation is underway to determine the source of the infection and identify additional horses that may have been exposed to the disease. This is the first EIA positive horse diagnosed in Idaho since 2005.

EIA is an infectious and potentially fatal viral disease of horses most commonly transmitted by biting insects. If not properly disinfected prior to use, needles and equipment contaminated with blood from an infected horse can also spread the virus to unexposed horses. At this time, there is no vaccine available to prevent infection or any medical treatment that is effective against the virus. Horses that do acquire the disease are infected throughout their life and will remain a source of infection to other horses in close proximity.

The symptoms of a horse infected with EIA are often subtle and may go unnoticed. EIA-positive horses may develop a low-grade fever or become lethargic as well as demonstrate weight loss, icterus (yellowing of body tissues), anemia, swelling in the limbs, and weakness. However, not all equids infected with the EIA virus show signs of illness, and these animals serve as inapparent carriers. Horses demonstrating clinical signs of EIA pose the greatest risk of spreading the virus due to the increased concentrations of virus circulating in the blood. Even inapparent carriers, though, may be a source of infection and pose a risk to other horses. Because of this risk, Idaho state law requires EIA-positive horses be euthanized or maintained under strict quarantine, isolated from all other horses, for the life of the animal. Most states require a test for EIA be conducted within the last 12 months of horses moving interstate. Horse owners are encouraged to incorporate an annual test for EIA (Coggins test) into their routine animal health regimen regardless of whether they travel interstate.

Thank You
Debbie Amsden
Executive Director