An infectious disease outbreak that began on April 23 at the Cañon City Wild Horse and Burro Facility, in Fremont County, Colorado, has resulted in the deaths of 85 horses, the Bureau of Land Management (BLM) confirmed April 28. Those gathered from the West Douglas Herd Area in fall 2021 are reportedly most impacted.

The BLM has placed the facility, which houses 2,550 horses, under voluntary quarantine and instituted strict biosecurity measures. Test results are pending for the yet unknown and highly contagious disease. Samples have been submitted to two equine veterinary diagnostic laboratories.

In the meantime, exposed horses and those showing signs of disease have been isolated from the herd, and independent and federal veterinarians are monitoring and treating them.

“We are working with local, state, and federal officials to determine what is impacting horses in the facility and how we can respond as effectively as possible,” said Stephen Leonard, BLM Colorado Wild Horse and Burro Program Manager, in a BLM press release.

The Colorado Department of Agriculture is working alongside the Colorado State Veterinarian’s Office, the U.S. Department of Agriculture, and the BLM to investigate the outbreak and monitor the horses’ well-being.