Update: On Saturday, the U.S. Equestrian Federation reported that a horse who had been at Desert International Horse Park within the past 14 days traveled to a competition in Rancho Murieta, California, and tested positive for EHV-1 while at that competition in Sacramento County. On the same day, organizers of the Northwest Winter Classic series, held at Murieta Equestrian Center in Rancho Murieta, which has been holding NWC II from Feb. 23-27, announced they are cancelling the last two weeks of their series, NWC III and NWC IV, in response to the EHV-1 situation.

Desert International Horse Park officials announced Friday that they have canceled all remaining shows scheduled for the winter season—Desert Circuit Weeks V to VIII and Desert Dressage IV—amid an outbreak of EHV-1 that has sickened more than 20 horses to date.

“We love horses and horse shows. But for now, our focus has to be on the care and safety of the horses here under isolation and quarantine and for those horses needing a home during this infection,” CEO Steve Hankin said in a Friday news release. “The horse park will remain open for all of these horses, especially those unable to find an appropriate place for further quarantine or where transport creates additional risk, until we are through this infection. We will take every precaution to continue to protect the horses here until we close for the season.”

New and suspected cases still are appearing on the Thermal, California, show grounds—one horse who previously tested negative came back positive on a re-test, and four new horses have been reported with elevated temperatures—but there is good news as well.

In his Friday statement, Hankin said two previously ill horses received their second consecutive negative test (each test taken seven days apart) and have been cleared to leave isolation, the first horses to do so. In addition, another 13 horses who were in quarantine have gone the required 14 days with exhibiting symptoms and were released from quarantine.

Per new U.S. Equestrian Federation protocols put in place Thursday to stem the spread of disease, all horses who have been on grounds at DIHP or in contact with those horses within the past 14 days must be isolated and have rectal temperatures taken twice daily. Horses who have been at DIHP in that time frame will not be allowed to enter any further USEF-sanctioned competition until they have either (1) two negative PCR nasal swabs taken at day seven and day 14 after leaving DIHP or (2) complete a 21-day isolation and receive a negative PCR swab after that time.

Noncompliance with these protocols will result in penalties imposed on trainers and owners as well as competitions that knowingly permit noncompliant horses on the grounds, USEF warned.

For more information on biosecurity best practices, click here.