The New York State Department of Agriculture and Markets has confirmed a case of equine herpesvirus-1 (EHV-1) and a case of equine herpesvirus myeloencephalopathy (EHM, the neurologic form of EHV-1) at a single facility in Schuyler County, the Equine Disease Communication Center (EDCC) reported Jan. 10.
“An aged Quarter Horse mare, displaying leaning and hind-end ataxia (incoordination), was confirmed positive for on a nasal swab PCR test late last week,” the EDCC said. “A few days later, a Quarter Horse gelding on the farm with only a high fever also tested PCR positive on a nasal swab for EHV-1.
“The mare, gelding, and all other horses on the farm are quarantined,” the agency added. “Biosecurity measures and temperature monitoring are in place. No horses have left the farm in the two weeks preceding the onset of the illness nor have left the farm after the diagnosis of the index case.”
The New York State Department of Agriculture and Markets will continue to monitor the situation.
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. In many horses, the first or 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.
Herpesvirus is easily spread by nose-to-nose or close contact with an infectious horse; sharing contaminated equipment including bits, buckets, and towels; or clothing, hands, or equipment of people who have recently had contact with an infectious horse. Routine biosecurity measures, including hygiene and basic cleaning and disinfection practices, should be in place at all times to help present disease spread.
Current EHV-1 vaccines might reduce viral shedding but are not protective against the neurologic form of the disease. Implementing routine biosecurity practices is the best way to minimize viral spread, and the best method of disease control is disease prevention.