Kentucky animal health officials have confirmed several cases of equine herpesvirus-1 (EHV-1) in horses residing at The Thoroughbred Center, in Lexington.

In a Feb. 14 statement, E.S. Rusty Ford, equine operations consultant for the State Veterinarian’s Office, said the affected horses were housed in Barn 3.

“The index case was reported on Tuesday evening, Feb. 13, after a horse that had presented with fever of unknown origin was sampled and results of PCR testing identified the horse to be positive for EHV1 ‘wild type’ on both nasal wash and whole blood,” Ford said. “The barn was immediately secured with no horses being allowed to move into or out of the barn. In addition to securing the barn with 24-hour guard assignment, a sanitizing area outside the barn’s entrance has been established and all individuals entering and leaving the barn must properly clean and disinfect and dispose of personal protective clothing that is provided on entry into the barn.”

Ford said 18 horses, including the index case, were stabled in Barn 3.

“Two horses that moved out of the barn prior to the discovery are currently in isolation on a private farm,” he added.

On Feb. 14, official emptied and secured a barn at The Thoroughbred Center to serve as a quarantine barn to isolate positive horses.

“Samples collected from the exposed horses earlier today have been partially reported, and has identified six additional positive cases,” Ford said. “Five horses were positive on nasal swab only and one was positive on both blood and nasal swab. In addition to the horses exposed in the barn, the outriders have been sampled and they too were reported negative.”

He added that he and State Veterinarian Robert Stout, DVM, assessed environment and situation, and “we continue to be of the shared opinion that the procedures and protocols put in place are being properly implemented and do provide us opportunity to contain the virus.”

Meanwhile, Ford also provided an update on the EHV-1 quarantine at Turfway Park, in Florence, roughly 70 miles from The Thoroughbred Center.

“There have been no fevers (or) any other evidence of illness reported in the quarantine barn at Turfway Park, and going through the barn last night, I did observe the population as being bright, alert, eating and with no evidence of illness,” he said.

“Our plan is to collect samples (nasal swabs and whole blood) from each of the horses in the quarantine barn next week that could potentially qualify the quarantine and other restrictions to be released,” he added.

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 EHM (the neurologic form). In many horses, the only sign of EHV-1 infection is fever, 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.