The Utah Department of Agriculture and Food is investigating one confirmed case of equine herpes virus (EHV-1) and has placed a quarantine on a farm in Cache County.
Two other horses at the farm were euthanized after showing neurological signs consistent with the disease.
The virus is not transmissible to people.
The highly contagious disease in horses spreads rapidly, state officials said. The disease can cause respiratory and neurologic disease, and death.
The most common way for the virus to spread is by direct horse-to-horse contact. It also is spread through the air, contaminated equipment, clothing and hands.
Horse owners are advised to quickly report symptoms to their veterinarian.
In addition, event coordinators should contact their show veterinarian for recommendations on holding an event.
"As a precaution to Utah horse owners, I advise they take extra biosecurity steps to safeguard the health of their animals," said Bruce King, state veterinarian.
"Don't let your horses touch other horses, especially nose to nose. And isolate horses that return to the farm from a show or event," he said.
Symptoms include fever, decreased coordination, nasal discharge, urine dribbling, loss of tail tone, hind limb weakness, leaning against a wall or fence to maintain balance, lethargy and the inability to rise.
While there is no cure, the symptoms may be treatable.
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