The Montana Department of Livestock reported March 21 that a horse in Flathead County has been diagnosed with the neurological form equine herpesvirus, EHV-1, after developing clinical signs of the disease.

Based upon the travel history of the animal and the incubation period of the disease, the horse was likely exposed at an event in Ravalli County earlier in March. The Livestock Department is currently working with event organizers to inform other participants of the potential risk.

EHV-1 is naturally occurring in equine populations and may cause respiratory disease, abortion in mares, neonatal foal death and/or neurologic disease. There are two types of the virus responsible for outbreaks in the U.S. – the neuropathogenic form, and the wild type. The horse in question appears to be infected with the less virulent strain, which is not as likely to cause neurological or severe clinical symptoms.

According to assistant state veterinarian Dr. Tahnee Szymanski, the affected horse developed weakness, which progressed into recumbency (inability to rise or stand) two weeks after attending the event.

The infection was confirmed by blood and nasal swab samples. An encouraging sign is that the affected horse seems to be improving, Szymanski said.

“At this time, this incident of EHV-1 is limited in scope, but there remains a possibility for additional cases,” Szymanski said.

Local horse owners are encouraged to contact their veterinarian if they suspect their horse may be affected with EHV-1. For more information, contact Szymanski at [email protected] or 406-444-2043.