Late on Jan. 12, the entire Fair Grounds Racetrack facility, in New Orleans, Louisiana, was placed under quarantine by State Veterinarian Brent Robbins, DVM, as a result of spreading equine herpesvirus-1 (EHV-1).

“This quarantine is being implemented out of an abundance of caution as we work to contain the disease,” said Louisiana Department of Agriculture and Forestry (LDAF) Commissioner Mike Strain, DVM. “While there has been restricted movement of horses at the racetrack, at this point, we cannot risk horses possibly leaving the Fair Grounds while some are still testing positive for the virus.

“This quarantine is being done for the health and safety of all horses in the state and to protect the horse racing industry,” he continued. “This virus is highly contagious and we still have horses showing symptoms of illness. We must do everything possible to contain this virus and continue testing until all horses are cleared.”

The Equine Disease Communication Center (EDCC), on Jan. 13 reported that “to date, test results report that 38 horses tested positive for EHV-1 non-neuropathogenic strain and two tested positive for EHV-1 neuropathogenic strain.”

On Jan 14, the EDCC reported that “on Jan. 13, a new case in Barn 45 at the Fair Grounds racetrack was moved to isolation.

Additionally, the LDAF said that 65 ship-in horses that were possibly exposed to an EHV–positive horse in the receiving barn have been traced, placed in isolation at undisclosed locations, and are being tested.

Horses in barns not exposed to EHV-1 will be allowed to continue racing, the LDAF said. Exposed horses under quarantine are monitored for at least 14 days and tested twice for EHV-1. Any horses that test positive for the disease, are placed in isolation for further observation and testing.

The LDAF continues to closely work with the USDA Veterinary Services, the state racing commission, Fair Grounds officials, and horse owners and trainers.

The LDAF said that, according to its records, EHM was last detected at the racetrack in 2008.

Herpesvirus is highly contagious among horses and can cause a variety of ailments in equids, including rhinopneumonitis (a respiratory disease usually found in young horses), abortion in broodmares, and myeloencephalopathy (the neurologic form). In many horses, fever is the only sign of EHV-1 infection, which can go undetected.

In addition to fever, other common signs of EHV-1 infection in young horses include cough, decreased appetite, depression, and a nasal discharge. Pregnant mares typically show no signs of infection before they abort, and abortions usually occur late in gestation (around eight months), but can be earlier. Abortions can occur anywhere from two weeks to several months following infection with EHV-1.

Horses with the neurologic form usually have a fever at the onset of the disease and might show signs of a respiratory infection. A few days later, neurologic signs such as ataxia (incoordination), weakness or paralysis of the fore- and hind limbs, urine retention and dribbling, loss of tail tone, and recumbency (inability to rise) develop.