New veterinary cases of equine herpes virus stamped out in California, Tennessee

National Report

— Two outbreaks of equine herpesvirus (EHV-1) have been contained after surfacing in California and Tennessee.

In Tuolumne County, Calif., eight horses on one premise were confirmed positive for the neuropathogenic strain of EHV-1. The EHV-1 source premise was placed in quarantine on Sept. 12. Six of the horses displayed neurologic signs, and two other horses just presented with fever. One of the eight horses was euthanized, according to officials from the California Department of Food and Agriculture (CDFA). Owners of the horses that visited the affected premises within two weeks prior to the outbreak have been notified by CDFA and asked to isolate and monitor their horses for signs of equine herpesvirus for 14 days. As of Oct. 3, no new cases had been confirmed.

In San Joaquin County, Calif., two more horses were confirmed positive for the neuropathogenic strain of EHV-1. Both horses were exposed to the virus between Sept. 4 and 10 while visiting the Tuolumne County premise, according to CDFA. One of the horses displayed neurologic signs, while the other presented with a fever only. CDFA believes there is minimal risk of disease spread beyond the facility due to early detection and immediate isolation of the horses.

The latest California cases of EHV-1 are not believed to be linked to prior EHV-1 cases emerging in September, affecting three horses and exposing 13 more.

The University of Tennessee Veterinary Medical Center lifted its 14-day quarantine Sept. 30 after an EHV-1 infected horse was brought to the hospital for treatment. That horse was later euthanized, and another five cases have been confirmed at the horse’s home ranch. Veterinary officials with the Tennessee Department of Agriculture quarantined the ranch and continue to monitor for new cases. The five horses confirmed with EHV-1 are also recovering, according to spokesperson from the state veterinarian’s office.