A quarantine of horses at Monmouth Park for cases of equine herpesvirus (EHV) was partially lifted today after tests on two horses showing possible signs of the disease last weekend came back negative.

With those two horses testing negative for the virus, the quarantine was lifted on horses in the “general population” barns at Monmouth. Since the quarantine was instituted on October 26, none of the horses from the general population have become infected with the virus. Those barns housed roughly 1,000 horses.

“No other horses from the general population with any clinical signs consistent with the disease have tested positive for more than 12 days since the inception of the quarantine, so we feel confident we can let them leave Monmouth Park,” state veterinarian Nancy Halpern, DVM said. “However, the quarantine remains on approximately 100 horses who either tested positive or were directly exposed to infected horses.”

The quarantine was instituted when at least four horses tested positive in late October after they began exhibiting fevers. Those four, and other horses at Monmouth Park that had contact with those horses, were separated from the rest of the equine population there and put in designated quarantine barns. All horses in the quarantined barns at the park will not be permitted to move to other facilities until they have shown no indications of the disease for at least 21 days.

During the quarantine, horses in the general population barns were allowed to leave Monmouth only to race at the Meadowlands and then be brought directly back to Monmouth. All movement was to be conducted using strict biosecurity measures, such as cleaning and disinfecting transport vehicles both before and after movement of a horse and prohibiting the sharing of equipment between horses unless absolutely necessary.

Last weekend, the two horses from the general population became a concern after one showed neurologic signs and the other registered a fever. However, the negative test results have relieved that concern and the general population horses may be released from quarantine.

The EHV-1 organism spreads quickly from horse to horse and can cause respiratory problems especially in young horses, spontaneous abortions in pregnant mares, and the neurologic form of the virus can reach high morbidity and mortality rates. The incubation period of EHV-1 is typically 2-10 days.

“With a disease like EHV, which can move rapidly through the equine population, you cannot take chances,” New Jersey Secretary of Agriculture Charles M. Kuperus said. “Although this disease is not harmful to humans, it can devastate an equine population. We have worked cooperatively with the New Jersey Sports and Exposition Authority and the New Jersey Racing Commission to enact an effective quarantine that also took into consideration the impact a quarantine would have on the horseracing industry in New Jersey.”

For more information on EHV-1, check out our free PDF library of EHV-related articles including images, or all our archived EHV-1 articles on TheHorse.com