Vaccination is the best defense for horses against mosquito-borne West Nile virus, said Mark Russell, assistant professor-equine Extension for the University of Arkansas Division of Agriculture.

Russell said he knows of one case of equine West Nile so far in Arkansas.

“Older and very young horses are the most vulnerable to the virus,” Russell said Monday. “Both vulnerable populations can be vaccinated more than once a year to ensure they’re covered.”

The good news is that the disease is not transmitted from horse to horse, or between horses and humans.

Next to vaccinations, using insect repellents and using fans and opening windows and doors to keep air moving around horses in the barn can help discourage mosquitoes.

“Use oil-based fly spray that contains lanolin. It’ll stick with the horses much longer than a water-based spray,” Russell said. “You put the same amount on and it lasts longer.”

One worry is Isaac, which is expected to hit Arkansas later this week as a tropical depression.

“We may get a lot of rain and we need to be thinking about that right now because we might be seeing more standing water and puddles this week,” he said. Mosquitoes breed in standing water. “There could be a spike in the mosquito population in the next two or three weeks.”

Russell said to be sure to drain any areas with standing water to prevent mosquito breeding.

He also advised horse owners to pay a little extra attention to details when looking over the herd.

“Symptoms of a West Nile infection include lethargy,” Russell said. “They look dazed and confused.”

Other symptoms include a high temperature, not eating or drinking, or problems with gait, including staggering or balance issues even when standing still. Other signs include muscle twitch, paralysis in hind limbs, impaired vision and inability to swallow.

“If anything looks odd, call the vet,” Russell said.

West Nile is a virus that is transmitted from infected birds through mosquitoes that feed on their blood.

For more information on insect control, see “Mosquito Control Around the Home and in Communities,” here, or contact your county Extension office.