A Colorado horse that was being routinely tested for movement out of the state was found to have equine infectious anemia, a viral disease for which horses must be either quarantined for life or euthanized. The horse was culled.
Additional investigation by USDA uncovered that this horse was associated with an EIA-positive herd in California participating in unsanctioned racing, the Colorado Department of Agriculture reports. 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 where the horse was being kept and no neighboring horses within 200 yards of the positive horse, so a quarantine of the facility has been released, officials said.
“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," she said. "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 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, notes the CDA.
Signs of disease
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.
Ag officials suggest these 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.
Equine herpesvirus detected
The infection comes after a horse from Clackamas County, Ore., recently tested positive for equine herpesvirus (EHV-1). After exhibiting neurologic symptoms, the owners called a private veterinarian to examine the animal and collect a sample for testing, according to the state Department of Agriculture. The horse was ultimately culled.
Its owner reports the animal recently traveled to the 2022 State Oregon High School Equestrian Teams Championship, held in Redmond, Ore., in mid-May. A second horse from the same ranch who also traveled to OHSET was recovering from initial respiratory symptoms, but an ODA veterinarian placed a quarantine on the farm following state and national guidelines.
State and event officials were working to evaluate the potential exposure risk to other horses that attended the championship.