An outbreak of equine herpesvirus type 1 (EHV-1) neurological disease has occurred on an Oregon farm. At last report, five horses had tested positive for the virus (though it’s not clear if all of them had neurological disease) and one had died.

EHV-1 outbreaks are not exactly rare these days. There’s certainly more reporting of sporadic disease and outbreaks, but it also seems like there’s been a true increase in outbreaks over the past 10-15 years. During my residency, we saw EHV-1 neuro cases not uncommonly, but almost always as single cases. Now, clusters like this are more common, for no clear reason.

Anyway, this outbreak appears to be contained, and it’s good that there’s been no movement on or off the farm in a while. This will likely end up being a sporadic, contained cluster on a farm with no broader implications. Since EHV-1 is very common, being found in the majority of horses, there’s always some risk of disease occurring.  That’s one of the main challenges we have in understanding and controlling this virus.

Tracking of EHV-1, and other equine (and dog and cat) diseases will soon be available on Worms & Germs MAP.  Stay tuned.