The Colorado Department of Agriculture (CDA) has confirmed two separate cases of Equine Infectious Anemia (EIA) in the state—one in Douglas County and another in Jefferson County. The incurable disease led both horse owners to make the difficult decision to humanely euthanize the affected animals, according to a recent CDA statement. Despite these incidents, officials currently consider the overall risk to Colorado’s equine population to be low.

The first case, involving a pregnant mare, was identified in Douglas County on April 5. The mare had recently arrived in Colorado and was tested as part of a routine health check. The U.S. Department of Agriculture’s National Veterinary Services Laboratory confirmed the diagnosis on April 10. The CDA noted that this case has ties to a widespread EIA outbreak in Texas, which occurred between May and September 2024. That outbreak was linked to improper sanitation practices at a veterinary clinic, which allowed the disease to spread among equine patients. While no other exposed horses have been identified in Colorado at this time, investigations remain ongoing.

A second horse tested positive in Jefferson County after undergoing routine testing for a Certificate of Veterinary Inspection prior to travel. The initial suspicion was raised on April 9, and confirmation from the USDA came on April 15. Horses potentially exposed to this case have been placed under quarantine and are currently being tested, the CDA reported.

Colorado State Veterinarian Dr. Maggie Baldwin emphasized the importance of strict hygiene and disease prevention in veterinary settings. “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.” Baldwin stated.

“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,” the agency said Thursday.

EIA is primarily transmitted through blood-to-blood contact, often by large biting insects or through unsanitary medical equipment, such as reused needles or instruments shared between animals.

Horse owners should consult with their veterinarians about appropriate testing and biosecurity practices to help prevent the spread of EIA and protect the broader equine community.

Author: Una

Una moved to Colorado in 2007 and started the Colorado Horse Forum as a way to meet other equestrians in the area. Una now rides and competes in dressage. She operates a small dressage horse breeding program in Castle Rock.