Officials at the Texas Animal Health Commission (TAHC) confirmed two Quarter Horses in Harris County with equine infectious anemia (EIA) on March 26. The premises has been quarantined until TAHC’s requirements are met, and the owner and local veterinarian are working closely with TAHC staff to implement biosecurity measures and monitor horses that were potentially exposed. The affected horses have been euthanized.

Equine infectious anemia is a viral disease that attacks horses’ immune systems. The virus is transmitted through the exchange of body fluids from an infected to an uninfected animal, often by blood-feeding insects such as horseflies. It can also be transmitted through the use of blood-contaminated instruments or needles.

A Coggins test screens horses’ blood for antibodies that are indicative of the presence of the EIA virus. Most U.S. states require horses to have proof of a negative Coggins test to travel across state lines.

Once an animal is infected with EIA, it is infected for life and can be a reservoir for the spread of disease