The Equine Disease Communication Center reported on March 25th that a veterinarian confirmed a case of equine herpesvirus (EHV) in a horse at a boarding stable in Foothills County, Alberta. The horse showed acute neurological signs, was treated for two weeks, but had to be euthanized after no signs of improvement were evident. The stable was placed under quarantine for three weeks but no illness was detected in the remaining horses who had been exposed.
EHV is a highly-contagious infection spread by close contact and contaminated equipment that can cause the respiratory disease rhinopneumonitis, late-term abortion, and equine herpesvirus myeloencephalitis or EHM, which is the neurologic form. Symptoms present as fever, cough, and nasal discharge, as well as depression and decreased appetite. With EHM, horses display fever and signs of respiratory infection, followed days later by incoordination and weakness or paralysis of the legs which can lead to the inability to stand.
EHV is common throughout the world; almost all horses have been infected with the virus at some point, but had no serious side effects. It is not known why some infected horses develop the serious and possibly fatal neurological form which the available vaccines do not protect against.