Wild Horses from the last year’s Sand Wash Basin roundup last November at the Cañon City corrals. Photo by Mark Neitro, CBS4. To read CBS4’s story about the corrals, see the link in the post below.

Update: 143 wild horses have died, as of Friday, May 13, according to BLM.

Fifty-seven wild horses have died from an “unknown yet highly contagious and sometimes fatal disease” at the Bureau of Land Management’s crowded Cañon City (Colo.) corrals, which the BLM said in a Monday press release are now under a voluntary quarantine.

The BLM said that is working with local, state and federal officials to determine what disease is killing the horses and how best to respond.

The outbreak began April 23, according to the BLM. Wild horses hit hardest by the outbreak are among the 457 captured last summer on the West Douglas Herd Management Area in Colorado. Other wild horses known to be housed at Cañon City include horses removed from the Red Desert Complex, Little Colorado Herd Management Area and White Mountain HMA, all in Wyoming, and from Colorado’s Sand Wash Basin HMA (Colo.).

There are currently 2,550 wild horses at the off-ranging holding facility at the East Cañon City Prison Complex. Elsewhere on its website, the BLM says that the corrals there can house up to 3,000 animals.

Cañon City has faced allegations of mistreatment in recent months, including of underweight horses standing in mud and muck.

As of February, the BLM was warehousing 60,611 wild horses and burros in off-range facilities, 21,784 of them in often overcrowded corrals.

BLM plans to capture and remove a record 19,000 wild horses and burros from the range during this fiscal year while treating just 2,300 with fertility control — a plan that we’ve said repeatedly is all the more irresponsible because BLM lacks the infrastructure, staff and contracts to run its own program, much less properly protect and care for captured wild horses and burros that the agency should be moving to more natural, cost-effective pastures.

The BLM should also be focusing on implementing a robust program of proven, safe and humane fertility control that can delay, reduce the size of and eventually replace removals as the agency’s primary management tool.

Cañon City is one of five facilities in the nation with a Wild Horse Inmate Program, under which inmates care for and train horses for adoption. Its location at the prison has kept the corral facility largely out of the public eye, though a news crew was granted access last November.

Return to Freedom would like to remind horse owners that a newly received horse or horse returning from horse shows, fairgrounds and the like should be housed where they do not have contact with other equines until it’s clear they have no symptoms.

Strangles and equine herpes are among the diseases that spread easily. Recently, the horse community has been warned by officials about outbreaks of equine herpes in certain areas and at showgrounds. It’s important to check with your veterinarian and have safe practices in place.