SALT LAKE CITY — Utah State veterinarian Barry Pitman is warning horse owners to take protective action to ward off a potentially fatal outbreak of equine herpes.

Fears of an outbreak reaching Utah prompted the cancellation of multiple high school rodeos as owners try to prevent the spread of the virus, which caused more than 160 horses to be euthanized in 2011-12.

"First and foremost, there have been no confirmed cases of EHV-1 or EHM in the state of Utah," Pittman said. "However, considering the cases in surrounding states, the nature of the virus and the commingling and stress levels of horses in event circuits, we are certainly susceptible to future cases."

As of March, the Equine Disease Communication Center reported three premises, two in New York and one in Washington, impacted by the equine herpes virus. Seven premises logged cases of the mutant strain of the virus as of March in Arizona, Idaho, Iowa, California and Nevada. The mutant strain is called equine herpes virus myeloencephalopathy, which impacts the central nervous system.

In April there have been sporadic cases in additional states as well as Canada.

Although nearly all horses are infected with the virus at a young age and are carriers with no symptoms, the virus can be reactivated under stress in events that include strenuous exercise, long-distant transport or at weaning, Pittman said.

"This means there will never be an 'all clear, no further risk,' as long as horses are brought together from multiple geographic locations," Pittman said.

He urged horse owners across the state to seek information from reliable sources, contact managers of events they plan to enter, increase health checks of their animals and stay at home if they don't feel comfortable traveling with their horses.

Pittman, who works for the Utah Department of Agriculture and Food, credits biosecurity measures by organizers at Utah events, the postponement or cancellation of some events and voluntary withdrawal from some events as multiple factors that have kept the contagious virus out of the state thus far.

Equine herpes is not a sexually transmitted disease and is passed through nose contact among infected horses, mules or burros. It is also spread through contaminated equipment, such blankets or buckets. Humans can't catch it.

Symptoms include fever, decreased coordination, nasal discharge, loss of tail tone, hind limb weakness and leaning against a fence or wall to maintain balance. Animals become lethargic and my be unable to rise from the ground.

Pittman said a horse from southern Utah had competed at a stallion futurity in Las Vegas, was possibly exposed and had to be euthanized.

The veterinarian doing the testing on that animal ruled out the mutant strain of the herpes and West Nile virus as well, so additional testing is being done. Pittman said student athletes building competitive points or trying for scholarships on the rodeo circuit are being the most negatively impacted.

In Nevada, Steve Stallworth, general manager of the South Point Arena and Equestrian Center, said they will "exercise extreme caution" but will continue to host upcoming events as scheduled.

"Safety and security are a priority," Stallworth said in a statement. "We are working closely with the state veterinarian and our own in-house veterinarian to ensure all precautions and necessary disinfecting measures have been made to the entire facility."

Additional information is available online at the Equine Disease Communication Center.

Contributing: Associated Press