Additional cases of equine herpesvirus-1 (EHV-1) have been diagnosed in connection with the ongoing outbreak believed to stem from a national championship cutting show. The competition, which was held in Utah, saw horses disburse to 20 western states and provinces. There are now confirmed cases in 10 states and 1 province.

Although it’s not transmissible to humans, EHV-1 is highly contagious among horses and camelids, and it is generally passed from horse to horse via aerosol transmission (when affected animals sneeze/cough) and contact with nasal secretions. The disease can cause a variety of ailments in equines, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and myeloencephalopathy (EHM, the neurologic form). Myeloencephalopathy is characterized by fever, ataxia (incoordination), weakness or paralysis of the hind limbs, and incontinence.

The USDA began tracking the outbreak in mid-may and yesterday released a new situation report, which can be viewed online.

At press time (June 3, 4:00 p.m