The Kentucky State Veterinarian’s Office reported late Jan. 24 that testing has confirmed additional equine herpesvirus-1 (EHV-1) cases at Turfway Park, in Florence, and Keeneland Race Course, in Lexington.

Testing was conducted after a mare previously stabled at Turfway Park tested positive for the wild strain of EHV-1 late last week.  

At Turfway Park, E.S. “Rusty” Ford, equine programs manager for the State Veterinarian’s Office, said, “the sampling of horses in the affected barn … did identify two additional horses (from one trainer—a 4-year-old Thoroughbred gelding and a 9-year-old Thoroughbred mare) to be EHV-1-positive by PCR detecting the ‘wild strain’ of virus from nasal swabs.”

Ford said there have been “no clinical developments in the horses currently housed in Barn 27 and options for removing those two positive horses from the environment and managing the barns remaining population are being evaluated and considered tonight.”

Meanwhile, at Keeneland, “whole blood samples were submitted from the population of horses in both of the previously quarantined barns today, and testing completed earlier this evening has identified a single positive EHV-1 horse (a 3-year-old Thoroughbred colt) in one barn,” Ford said. “That positive horse has been removed from the barn and is in a secured isolation.”

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He said testing of nasal swabs collected from each horse in the barn is expected to be completed Jan. 25.

“The population of horses continues to be confined to the barn pending results of that testing,” he said. “Testing of samples completed on horses in the second quarantined barn have been reported negative on blood only and they too remain confined to the barn until testing of nasal swabs is complete.”

Ford said all affected barns are secure and movement into and out of them has been restricted to essential personnel only.

“Biosecurity measures have and continue to be implemented at the highest level at each track and we are of the opinion tonight that recognizing and responding to the disease risk early in this united manner has been effective at both tracks and does provide the opportunity to resolve the disease threat in the coming weeks,” he said.

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.