After the Oklahoma Department of Agriculture, Food and Forestry announced a case of equine herpes myeloencephalopathy or EHV-1 “A” strain after returning to Texas from a barrel race event, the equine world has been on alert.
Equine herpes is not the only infectious disease known to affect stock in Oklahoma. Just a week prior to the EHV-1 notification, the ODAFF released a statement reminding horse owners to vaccinate against rabies and West Nile due to the risks associated with loss of stock when these preventative measures aren’t taken.
The horse affected with EHV-1 competed at the Better Barrel Races World Finals in Oklahoma City April 26 to 29th and also a barrel racing event in Taylor, Texas on May 5,” Assistant State Veterinarian Michael Herrin, D.V.M. said.  “We do not know when or where this horse may have first started shedding virus, but out of an abundance of caution we want to make horse owners, event managers, and veterinarians aware of this situation.”
“To my knowledge there hasn’t been an equine herpes case in Oklahoma, “ said Dr. Barry Whitworth, DVM, the OSU Extension  Area Food/Animal Quality and Health Specialist for Eastern Oklahoma. “This is currently just a caution to watch any exposed animals and make sure they aren’t exhibiting symptoms.”
There are different types of equine herpes, Whitworth said. “There is one that can cause neurological issues, but it is far more common to see the respiratory issues, like nasal discharge and fever. Neurological  signs may still occur along with the respiratory type if it progresses and infects the brain.” While there is a vaccine for EHV-1 currently on the market, it is only indicated to protect horses against the respiratory type.
The Animal Industry Services division of the ODAFF has encouraged horse owners to take precautions against several diseases, including EHV-1. In previous years, Oklahoma has averaged about 40 cases per year of mosquito-carried diseases in horses. Mosquitoes can transmit certain diseases to both horses and humans. They can lay eggs in pools of standing water, which then exacerbates the problem once the adult mosquitoes hatch. Birds carrying the virus can spread diseases such as West Nile and Eastern Equine Encephalitis with a much further reach than just mosquitoes alone.
“Signs of West Nile Virus include weakness, fever, incoordination, seizures, blindness and difficulty getting up,” said Herrin. “There are several vaccines available, and we are encouraging horse owners to visit their veterinarians and determine the vaccination protocol that will best fit their operations.”
Oklahomans can reduce the number of mosquitoes by limiting standing water. Turning buckets, wheelbarrows, etc., upside down to prevent standing water helps keep egg laying and hatching to a minimum. In addition, ODAFF recommends vaccinating horses against Tetanus, Equine Herpes virus, Equine Influenza, and Rabies.
 ODAFF recommends horse owners and event managers remain at a heightened level of awareness, implement biosecurity practices to minimize potential exposure, consult with a veterinarian on an appropriate vaccination schedule, and report any suspicious illness or neurologic disease.
Whitworth said it is best to implement biosecurity practices any time you take an animal off your place and go to an area where you’ll be around other animals. “When you return home with that animal, that animal should be isolated for a couple weeks, or ideally 30 days,” Whitworth said. This applies not just to equine stock, but other show or competition animals including dogs, cattle, and smaller livestock like goats and sheep. Whitworth said it is most important to isolate animals to prevent exposure. He also said it’s important to make sure clothing, boots, and equipment used at shows and during travel are adequately and thoroughly cleaned before any other animals are around them. And he said it’s best  to prevent contamination at shows by not sharing equipment and preventing contact between animals.  For updated information about equine diseases, including details about the conditions and vaccinations mentioned above, visit the Equine Disease Communication Center at equinediseasecc.org. Report any suspicious illness to your veterinarian or the Oklahoma Department of Agriculture Food and Forestry: Dr. Michael Herrin, (405) 522-6142, michael.herrin@ag.ok.gov.