BROOMFIELD, Colo. — The Colorado State Veterinarian’s Office has received confirmation that a horse in Pueblo County tested positive for equine infectious anemia (EIA). Samples from the horse initially tested positive at the Colorado State University Veterinary Diagnostic Laboratory on June 2, 2022. A second sample was collected and the EIA-positive results were confirmed by the USDA’s National Veterinary Services Laboratory on June 14, 2022.

The horse had been moved to the Pueblo County premises two weeks prior and was being tested for movement purposes. It was not showing clinical signs of EIA at the time of testing and was likely an inapparent carrier of the virus. There is no vaccine or treatment for EIA and infected animals must be quarantined for life or euthanized. The EIA-positive horse was euthanized on June 15, 2022.

Additional investigation by USDA uncovered that this horse was associated with an EIA-positive herd in California participating in unsanctioned racing. It is unknown when and how the horse arrived in Colorado. Unsanctioned racing is known to be associated with high risk practices for transmission of EIA. There were no additional horses on the Pueblo County premises and no neighboring horses within 200 yards of the positive horse, so the quarantine has been released.

“Horses involved in unsanctioned racing are at significantly higher risk to contract and spread equine infectious anemia virus, primarily due to risky practices such as improper use of needles and equipment. These cases highlight the need for continued surveillance, monitoring, and education about the disease,” said State Veterinarian Dr. Maggie Baldwin. “The risk to the general equine population in Colorado is low at this time, however EIA is a deadly disease with no vaccination or treatment. Surveillance is a critical part of disease control for this particular virus. Horse owners should maintain a current Coggins test on their horses and practice good biosecurity measures when traveling with their horses.”

EIA is a viral disease spread by blood feeding flies (horse flies and deer flies), inappropriate use of needles or other blood-contaminated equipment used between susceptible equine animals such as horses, mules and donkeys. Clinical signs include high fever, weakness, weight loss, an enlarged spleen, anemia, weak pulse, and even death. However, many infected equines do not appear to have any clinical signs of the disease and serve as a reservoir, putting other animals at risk. EIA does not cause disease in humans.

Equines (horses, donkeys and mules) must be tested annually for EIA before they can be transported across state lines. It is also recommended that all equestrian shows, rodeos, fairs, and other equine events consider requiring a negative Coggins test for entry, even if the horses haven’t crossed state lines. Coggins tests are also recommended as an important component of a pre-purchase exam.

Biosecurity tips for horse owners:

Separate symptomatic horses and contact your veterinarian immediately.

Don’t commingle your horse with other, unfamiliar horses.

Do not share surgical or dental equipment that are contaminated with blood or debris between horses.

Keep the area in and around your barn clean and dry to reduce the insect population.

Apply fly sprays and insect repellents as needed.

Work with your veterinarian to test your horses annually for EIA.

More information about equine infectious anemia can be found on the CDA website or the USDA website.