Concern and rumors over an outbreak of equine herpes virus-1 tied to a cutting-horse event in Ogden from April 29 through May 8 continued to grow throughout the day Monday as more cases were confirmed and suspected.
One Colorado horse was confirmed to have been euthanized because of the disease.
Local and national events were canceled, including a Utah Quarter Horse Association show scheduled for Saturday at Golden Spike Event Center in Ogden.
Five horse farms were quarantined in Nebraska, according to The Associated Press.
Colorado State University closed its world-renowned veterinary teaching hospital in Fort Collins to all nonemergency appointments, according to Colorado State University website.
Warnings from local veterinarians and the Utah Horse Council gained momentum and were sent out and passed around with increased urgency throughout the state.
"The Golden Spike facility is not under quarantine at this time, but I would advise not going there until we get further information on the outbreak," states a warning on the website of Aspen Grove Veterinary Clinic in West Haven. "Additionally, any shows or events that would include horses from this show should consider postponing until a safe incubation period is over. This is 28 days according to the state veterinarian's office."
A Facebook message from the Utah Horse Council was titled "!!! URGENT EMERGENCY MEDICAL NEWS!!!!"
The message urged anyone who had taken their horse to the Ogden facility recently to check their horse carefully and consult their veterinarian.
State of Utah Veterinarian Bruce King said as of Monday there were confirmed cases of EHV-1 in Colorado, California and Canada.
"There are tests pending in six other states," he said. "I suspect they are all going to be positive."
King listed Arizona, New Mexico, Washington and Oregon as states where horses were showing signs of the disease, but veterinarians were waiting on laboratory testing for confirmation.
Officials with the Utah High School Rodeo Association also said they believe a horse owned by one of their members had contracted the disease.
Officials from several horse groups said they were waiting on word from King to decide if they would cancel additional upcoming horse events.
"We want to do whatever is best for the industry," said Wade Woolstenhulme, president of the Utah High School Rodeo Association, which canceled two upcoming cutting contests.
"We as an association decided not to hold these last competitions, just because we don't want to lose the opportunity to compete in other places," he said.
Julie Anderson, who oversees all of the Weber County Junior Posses, said she is recommending that no practices of the posses be held until further notice.
King said the outbreak is believed to have occurred during the Western Nationals Cutting Show at Golden Spike Event Center.
"There were horses there literally from all over the Western United States and Canada," King said.
"There were about 500 horses there," he said, noting that horses came and went throughout the time of the show.
Among the shows canceled was the National Cutting Horse Association Breeder's Invitational in Tulsa, Okla., scheduled to have started Monday. The 15-day event was set to run through May 31.
The National Cutting Horse Association website recommended that those who had a horse competing at the NCHA Western National Championships in Ogden may wish to consult with their local veterinarian on this issue.
The site stated that symptoms typically show initially within four to six days of exposure to the virus, and initially are in the form of a fever in the affected animal.
A brochure from Utah State University Extension Service, available at http://extension.usu.edu/files/publications/publication/AG_Equine_2008-0..., states there are no antiviral treatments available for EHV-1.
It states that the disease can cause paralysis of the hind limbs of a horse, causing incoordination, gait abnormalities and in some cases the inability to rise from a sitting position.
The site warns that the virus has a unique adaptive mechanism that can become latent:
"Then at an opportune time (i.e., levels of high stress) the virus emerges and can be silently shed, infecting other horses that come into contact with the 'silent' shedder."
The National Cutting Horse Association website stated the association has been asked by veterinarians monitoring and working on the spread of the disease to do some data collection to help combat the further spread of the virus.
The site asks for owners or trainers of horses that exhibited neurological symptoms of EHV-1, had a fever without neurological signs of the virus or that have died from what they believe to be EHV-1 to contact the NCHA office.
Jim Harvey, manager of Golden Spike Event Center, said his workers went beyond what was required, cleaning and disinfecting all areas of the center once they learned of the outbreak. They also disposed of all hoses throughout the facility.
King said the disease in question was passed from horse to horse, and he confirmed that the center is not under quarantine.
"We have no reason to believe that that facility would be any more infective than any other facility where horses have been."