Two horses in Colorado have been diagnosed with Equine Infectious Anemia (EIA). The Colorado State Veterinarian’s Office received reports of two different horses with presumptive positive results of EIA, an incurable disease that impacts equines such as horses, mules, and donkeys. In both cases, the owners have made the difficult decision to euthanize the positive horses. The risk to the general equine population in Colorado is considered low at this time.
The first case was identified in Douglas County on April 5, where a pregnant mare was tested after traveling to Colorado. Confirmatory testing was completed on April 10 by the USDA National Veterinary Services Laboratory (NVSL). This case has been associated with a recent large EIA outbreak associated with a veterinary clinic in Texas between May and September of 2024. Improper hygiene practices are attributed to the transmission of disease between equine patients at the clinic. So far, no additional Colorado exposed horses have been identified, however the investigation is ongoing.
The second horse was confirmed positive on April 9 in Jefferson County, after it was tested at a veterinary clinic during an examination for a Certificate of Veterinary Inspection (CVI) before movement. Confirmatory testing was completed by USDA NVSL on April 15. Quarantine and testing of exposed horses have been initiated.
“The confirmed transmission in the Texas outbreak highlights the importance of strict disease prevention practices and routine EIA testing,” said Colorado State Veterinarian Dr. Maggie Baldwin. “This case is a sobering reminder of the potentially devastating and far-reaching consequences of failing to adhere to sanitary protocols. I encourage all Colorado veterinarians to review their practice’s sanitation protocols with their staff.”
An annual test for EIA, also known as a Coggins test, is recommended for all horses. Additionally, a negative EIA test as well as a Certificate of Veterinary Inspection, are required for any equine to cross state lines in the United States.
CDA strongly recommends that all equestrian shows, rodeos, fairs, and other equine events require a negative EIA test for entry, even if the horses haven’t crossed state lines, to further safeguard the equine population from potential disease spread.
More about Equine Infectious Anemia
Equine Infectious Anemia (EIA) is a viral disease spread by large biting insects or inappropriate use of needles or other equipment between susceptible equine animals such as horses, mules, and donkeys. Infected horses may not appear to have any clinical signs of the disease, although the virus can cause high fever, weakness, weight loss, an enlarged spleen, anemia, weak pulse, and even death. There is no cure for the disease, so infected animals must be quarantined for life or euthanized. EIA is not transmissible to people.
For additional information on EIA, please visit the USDA Equine Infectious Anemia website. EIA is a disease that is reportable to the Colorado Department of Agriculture, State Veterinarian’s Office. Visit the CDA website for guidance on reportable diseases.