One of the horses attended at show in North Salem on March 4-5.

An additional 45 horses at the affected Los Angeles County boarding facility are currently under quarantine.

A mare showed neurologic signs of the disease on March 1. Three days later a second horse, her neighbor, exhibited a fever.

Nearly 200 horses remain held at the competition venue in Valencia by government officials in Spain, where EHV-1 is a reportable disease.

The 3-year-old Thoroughbred’s training facility is under quarantine.

Officials have deemed the cases unrelated.

Outbreaks worldwide prompt enhanced biosecurity recommendations for equine events.

This case has not been connected with international travel, transport, or exhibition.

Both horses were recently stabled at the World Equestrian Center, in Ocala, during competition.

The equine herpesvirus-1 outbreak began at an FEI jumping competition in Valencia, Spain, with cases spreading to Belgium, France, and Germany. The FEI calls it “probably the most serious EHV-1 outbreak in Europe for decades.”