On the heels of the deadly equine herpesvirus type 1 (EHV-1) outbreak in Ohio came a report of a private farm in Canada with several horses dead of the same cause. Scott Weese, DVM, DVSc, Dipl. ACVIM, assistant professor of clinical studies at the University of Guelph’s Ontario Veterinary College, said Canada has had at least one big EHV-1 outbreak in the past six months, but sporadic “clusters” of EHV-1 cases are fairly common in Ontario. There have been a few standout, or “hot” strains that seem to have caused more morbidity (sickness rate) and mortality than other strains, so EHV-1 has received attention in Ontario recently.

“We looked at a cluster of cases the other day (at a private farm) with a lot of horses on a small piece of property, many of them geriatric,” said Weese. “It looks like a similar strain to that back in the October outbreak (based on clinical signs and outcome), and looks similar to the (current) Ohio strain,” something he suggests to be “hotter” than typical endemic strains