Virus slamming horse population
The recent outbreak of equine herpesvirus-1 (EHV-1) is raising alarm among many horse owners.
The outbreak, which appears to have begun at the National Cutting Horse Association Western National Championship in Utah, involves more than 34 infected horses from nine states.
While it is not uncommon for horses to be infected with a strain of EHV-1 in their lifetime, the particular strain in this outbreak is developing into the neurological form of the virus, known as equine herpes myeloencephalopathy (EHM). It is less common and more serious than other strains.
“When you look at the whole scope of things, it’s a very contagious virus,” said equine veterinarian Beth Davis at Kansas State University. “A horse can easily become infected from nose-to-nose contact with an infected horse.”
The virus can also be spread through contaminated equipment or tack and can be aerosolized in confined areas like stables.
Horses who develop EHM have a fever followed by neurological symptoms caused by damaged vessels decreasing blood flow to the brain and spinal cord. The USDA said these symptoms may include nasal discharge, decreased coordination, urine dribbling, loss of tail tone, hind limb weakness, leaning against a wall or fence to maintain balance, lethargy and inability to rise.
Davis said no virus exists to provide protection against EHM, but giving vaccines to potentially exposed horses may stimulate immunity to help their body deal with the virus.
According to the USDA report, 13 horses in the outbreak have developed EHM, with seven dying or being euthanized. Davis said horses with EHM have a 50 percent chance of recovering depending on the severity of the infection, though they may never be able to perform at the same level they did previously.
To prevent further spread of the virus, the USDA, American Association of Equine Practitioners and other organizations are encouraging horse owners to isolate horses that may have been exposed to EHV-1 or EHM and use separate feeding equipment and tack. They also recommend thoroughly sanitizing clothes, footwear and hands after working with potentially exposed horses.
Davis said she is encouraging horse owners to keep their animals at home to avoid commingling with other horses. Even group trail rides should be avoided.
“You can ride your horse at home. You can do what you do on the farm,” she said, “but I don’t recommend going to group activities until June 1 or even mid-June.”
Davis said by June she expects to have better predictions of the future of the outbreak. She said she is hopeful they will not see a dramatic increase in cases.
As a result of the outbreak, the National Cutting Horse Association has canceled dozens of its events scheduled through June 5. Many other horse events and rodeos throughout the country have been canceled as well.