Officials haven’t isolated the source of the disease, but the affected gelding competed at barrel races on Sept. 25, Oct. 2, and Oct. 5 at the Weber County Fairgrounds, in Ogden. Any horses that attended one or more of these events is considered potentially exposed. Officials advise their owners and/or handlers to isolate the horses, enact strict biosecurity procedures, and monitor the horses’ temperatures twice daily.
“We’re advising horse owners who have plans to attend events and competitions this season to practice diligent biosecurity,” said Chelsea Crawford, DVM, assistant state veterinarian, in a statement. “Limit or avoid horse-to-horse contact and use of shared communal water sources as much as possible, and disinfect shared equipment in between horses.”
Herpesvirus is highly contagious among horses and can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and EHM.
In many horses, the first or only sign of EHV-1 infection is fever, which can go undetected. In addition to fever, other common signs of EHV-1 infection in young horses include cough, decreased appetite, depression, and a nasal discharge. Pregnant mares typically show no signs of infection before they abort, and abortions usually occur late in gestation (around eight months), but can be earlier. Abortions can occur anywhere from two weeks to several months following infection with EHV-1.
Horses with the neurologic form usually have a fever at the onset of the disease and might show signs of a respiratory infection. A few days later, neurologic signs such as ataxia, weakness or paralysis of the fore- and hind limbs, urine retention and dribbling, loss of tail tone, and recumbency develop.
Herpesvirus is easily spread by nose-to-nose or close contact with an infectious horse; sharing contaminated equipment including bits, buckets, and towels; or clothing, hands, or equipment of people who have recently had contact with an infectious horse. Routine biosecurity measures, including hygiene and basic cleaning and disinfection practices, should be in place at all times to help prevent disease spread.
Current EHV-1 vaccines might reduce viral shedding but are not protective against the neurologic form of the disease. Implementing routine biosecurity practices is the best way to minimize viral spread, and the best method of disease control is disease prevention.