The California Department of Food and Agriculture (CDFA) released the equine herpesvirus-1 (EHV-1) quarantines in San Joaquin and Riverside counties on June 30.

The department reported June 16 that a 12-year-old Quarter Horse gelding and a 12-year-old mule, both from Riverside County, attended Mule Days in Bishop, California, which took place May 17-26.

“After returning home, the Quarter Horse gelding spiked a fever of 106°F on May 30 and exhibited neurologic signs on June 4 and confirmed positive for … EHV-1,” the statement said. “The 12-year-old mule never spiked a fever and began coughing on June 2 but showed no other clinical signs.”

The statement also said that an 8-year-old Quarter Horse gelding who did not attend Mule Days, but was a cohort to the other Quarter Horse gelding, developed a high fever and severe hind limb ataxia (incoordination) on June 4.

“His condition deteriorated, and he was euthanized on June 10,” the statement said. “He was affected with the neuropathogenic strain of EHV-1.”

The CDFA released the quarantine after no additional cases were confirmed and it had been at least 14 days since the gelding’s euthanasia.

Meanwhile, in San Joaquin County, there have been no additional EHV-1 cases reported since a 13-year-old Quarter Horse mare tested positive earlier this month. That mare did not attend Mule Days, but was exposed to two cohort mules after they arrived home from the event.

The CDFA said it released the quarantine after a second set of samples from five exposed horses and mules came back negative.

Herpesvirus i