Peak Hazard Months As Mosquitos Spread Deadly Virus To Horses

West Nile virus risk is increasing and will be at the highest level in the immediate weeks ahead.

“In 2016, there were 377 equine West Nile virus cases across the United States, an increase of 152 cases from a year earlier,” according to Dr. Kevin Hankins, senior veterinarian for Equine Technical Services at  Zoetis Animal Health.

West Nile virus is spread to horses by mosquitos and is fatal to 33 percent of horses exhibiting signs of the disease.

Horses are at the highest risk for contracting West Nile virus during peak mosquito season, which occurs July through October in the United States, he said

Previously, Hankins worked as head of equine field service at Kansas State University’s Veterinary Medical Teaching Hospital for seven year. He coordinated hospital outreach programs and student practice management programs.

“It’s not too late to help vaccinate and protect horses against this devastating disease,” Hankins insisted. “When properly vaccinated, horses have shown to be 30 times less likely to contract West Nile.

West Nile virus is transmitted by mosquitoes, which feed on infected birds, to horses, humans and other mammals, the veterinarian explained.

“The uptick in 2016 cases is likely due to the drought that occurred in 2015,” Hankins evaluated.

Droughts can increase numbers of small, stagnant pools of water, presenting ideal breeding grounds for mosquitoes.

“During a drought, bird populations often decrease,” Hankins continued. “As birds flock to wetter areas of the country, mosquitoes are left to feed on other warm-blooded animals nearby, such as horses.”

When considering the West Nile cases last year Dr. Hankins cautioned, “The numbers are likely much greater. Some states only report West Nile virus cases if the disease is presented in neurological form.”

For horses that have not been given shots or are overdue for immunization, proper vaccination can help provide the added protection horses needed to stay healthy.

In conjunction with vaccination, horse owners can help prevent West Nile by implementing proper horse management techniques, including:

Eliminate any mosquito-breeding habitats by removing all potential sources of stagnant water, such as unused troughs, wheelbarrows, ditches and tarps.

Hang fans throughout the barn where horses are stabled, as mosquitoes avoid moving air.

Clean and empty any water-holding containers on a weekly basis.

Apply insect repellent or bring horses inside from dusk to dawn, which are the peak mosquito feeding hours.

“West Nile does not always lead to signs of illness in horses,” Hankins said. “For horses that do become clinically ill, the virus infects the central nervous system and may cause symptoms such as loss of appetite and depression.”

Other clinical signs may include fever, weakness or paralysis of hind limbs, impaired vision, aimless wandering, walking in circles, hyper-excitability or coma.

“If horse owners notice signs or symptoms of West Nile infection in their horses, they should contact a veterinarian immediately,” Hankins said.

“West Nile virus is fatal in 33 percent of horses that exhibit clinical signs of disease,” he said

“Don’t take a chance by not protecting your horses against this devastating disease,” Hankins cautioned.