RENO, Nev. -- Concerned about the threat of a catastrophic outbreak of a herpes virus among wild horse herds in the West, national animal advocates on Thursday called on the federal government to keep potentially infected domestic horses away from mustangs and burros on public lands.
The Humane Society of the United States urged the Bureau of Land Management to "discourage and, if possible and appropriate, prohibit" owners of private horses from bringing animals at risk of Equine Herpes Virus-1 onto federal lands where they could have contact with wild horses.
"The potential for a catastrophic outbreak of EHV-1 among wild horse herds needs to be addressed by the BLM on an emergency basis," Holly Hazard, the society's chief innovations officer, wrote in a letter to BLM Director Bob Abbey.
The federal agency should launch a public education campaign immediately about the highly contagious disease, which has infected dozens of horses and killed at least nine, as officials plan horse-related activities for the upcoming holiday weekend, she said.
EHV-1 poses no risk to humans, but can be fatal to horses. It can be airborne and transmitted by touch or by sharing feed, brushes, bits and other equipment.
The virus "is a highly transmittable disease, and the symptoms don't show up immediately," Hazard told The Associated Press.
"You can have a horse that may have been exposed and you are not even aware they are carrying the virus. The most vigilant thing for everybody to do is enjoy their horses on their own property until the health officials have it sorted all out," she said.
Traced back to a cutting horse competition earlier this month in Ogden, Utah, the virus has been exposed to more than 1,000 animals through direct or indirect contact with infected horses. Symptoms include fever, decreased coordination, nasal discharge, loss of tail tone, hind limb weakness and inability to rise.
So far, no animals managed by the BLM are known to have been infected, BLM spokesman Tom Gorey said Thursday. He said the agency is considering limiting horse movement on a case-by-case basis and may cancel some scheduled adoption events.
The federal agency "has been working with state and federal animal health officials to help protect the health and well-being of wild horses and burros on the range, along with those in BLM holding facilities," Gorey said.
Horse owners should contact local BLM offices to see if there are any restrictions before bringing domestic horses onto federally managed public lands.
Tom Collins, a Clark County commissioner who owns horses and runs a cattle ranch outside of Las Vegas, said he felt the federal agency generally was taking the proper precautions but that prohibiting domestic horses on public lands in some areas was going too far.
"To tell people not to ride in areas that are public lands because of this horse virus, in my opinion, is a probably a little over cautious," Collins told AP. "It's probably more of a reaction to a request by the horse lovers than common sense. But at the same time, I can see their point, because it is airborne."
Since the virus was discovered, organizers of horse sales, rodeos and other competitions involving the animals have canceled or postponed events in Colorado, Kansas, Oklahoma, Oregon, Montana, Nevada, Utah and Washington. But some other major events are continuing as scheduled, including the College National Finals Rodeo June 11-18 in Casper, Wyo., and the Reno Rodeo June 16-25, billed as the fourth-richest rodeo on the Professional Rodeo Cowboys Association.
Animal health officials in Utah and Nevada are among those who are optimistic the worst of the outbreak already has run its course.
"There's not really anything earth-shaking that's happened to change what we're thinking," Dr. Bruce King, Utah's state veterinarian, said. "If we can get through the end of the month ... we will feel comfortable about holding equine events again."
But groups including the American Wild Horse Preservation Campaign have joined the call for "an abundance of caution ... because of the potential catastrophic consequences that could occur if the virus spreads to the wild horse herds."
"Given the serious nature of the virus and the already diminished population of mustangs in the west, the BLM needs to act quickly to ensure that the virus does not spread," campaign spokeswoman Deniz Bolbol said.
Hazard said there are a number of ways a wild horse could contract the disease even if it didn't have direct contact with an infected animal. For example, domestic horse owners are permitted to have hay on the ground for their horses at campgrounds on BLM lands, national forests and other U.S. lands, she said.
If an infected domestic horse ate that hay, mustangs that frequent campgrounds and other equine recreational areas may move in to eat the contaminated hay leftovers and be exposed to the disease, Hazard said.
"Since EHV-1 infections can be fatal," she said, "should such a scenario occur, the impacts on wild horse populations could be disastrous."
Associated Press writer Josh Loftin contributed to this report from Salt Lake City.