Horse Virus Corrals the Riding Circuit
Rodeos, Competitions and Exhibitions Canceled in Western States as Officials Struggle to Contain the Spread of Infection
DENVER—Veterinarians and horse owners across the West are struggling to contain a highly contagious and potentially deadly equine virus that has so far infected at least 34 horses in nine states, from Texas to Washington.
The outbreak of Equine Herpes Virus-1 has forced authorities to cancel or postpone many riding competitions, rodeos, fairground exhibitions and horse auctions in several Western states and Canada.
Among the casualties: The Breeder's Invitational, a two-week, "cutting horse" event in Tulsa, Okla., that typically draws hundreds of competitors vying for more than $1 million in prize money.
It was at another competition—a national championship held earlier this month in Ogden, Utah—that the virus first surfaced. That event drew 400 horses and riders who competed to show their flair at cutting a cow off from its herd.
One or more horses at the championship was infected with equine herpes and apparently transmitted it to other competitors, which then traveled back to their home paddocks and exposed some of their stable mates to possible infection, authorities said. In addition to the 34 confirmed cases, 60 horses have shown symptoms and are being tested.
In western Washington state, the Kitsap Mounted Posse—a group of about a dozen equestrians—pulled out of Saturday's Armed Forces Day parade in Bremerton at the request of local veterinarians who urged them to keep their horses home to avoid any chance of spreading the disease. The infection can incubate for up to three weeks, so it may be some time before all infected animals are identified.
"This outbreak is much more widespread than most, or perhaps any, previous outbreak," said Keith Roehr, the Colorado state veterinarian.
At least seven horses infected with the disease have been euthanized.
Horses can contract equine herpes from water, fences, tack or other equipment that has been contaminated with sneeze droplets from an infected animal. The disease poses no threat to humans but can spread to mules, burros, llamas and alpacas. Symptoms include lack of coordination and loss of balance, along with fever, weakness, lethargy and nasal discharge. Mortality rates vary widely, from 10% to as high as 75% of infected horses.
Equine Herpes Virus-1 has been around for decades and is quite common; a number of vaccines effectively control symptoms. But in the past several years, veterinarians in many states have reported outbreaks of a mutant form of the virus. The vaccine does not protect against this form of the virus. It's this mutant form that appears to be afflicting horses who attended the cutting-horse competition in Ogden, said Dr. Bruce King, Utah's state veterinarian.
The mutant form is treated with antiviral medications, but there's no sure-fire cure.
Officials in Utah and several other states have quarantined ranches housing horses infected by or exposed to the virus. In addition, Colorado is requiring all horses entering the state to present a clean bill of health from a veterinarian. The U.S. Department of Agriculture said there were 42 stables or farms across 18 states with suspected or confirmed infections on their premises.
Across the West, authorities are urging owners who brought horses to the cutting championship in Ogden to take their animals' temperature twice daily and report any fever at once.
"I'm sure there's a lot of disappointment" at the cancellation of so many events and competitions, said Jeff Hooper, executive director of the National Cutting Horse Association.
"But owners just have to wait it out. The health and safety of our horses is foremost on everyone's mind."
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