A 3-year-old horse stabled at Churchill Downs (Ky.) that began showing neurological signs Oct. 18 was confirmed to have a Herpes virus infection. The horse is hospitalized and is expected to recover. All other horses in his barn at Churchill Downs are under quarantine and tested negative for the virus.
This neurological form of Herpes (AKA Rhinopneumonitis virus) been behaving differently in recent years, with more horses showing severe neurological signs, often without any respiratory symptoms. It’s unclear whether this horse is one of the rare neurological complications or if it is infected with a strain of the virus that prefers the nervous system.
The Herpes virus is not hardy. Infection is usually limited to horses that have been in the immediate vicinity and rarely spread even to other barns on the same premises. Existing vaccines don’t provide good protection from disease but do often reduce the amount of virus a horse with an active infection spreads.