Clinical Signs of West Nile Virus

Nathan Slovis, DVM, an internal medicine specialist at the veterinary firm of Hagyard-Davidson-McGee in Lexington, Ky. diagnosed the first equine case of West Nile Virus (WNV) in Kentucky, and described the clinical signs of the virus to The Horse. The filly first began showing neurologic signs on Aug. 23.

Slovis said the filly was "drunk" and looked sedated on Aug. 23, but by the time she was admitted, she no longer had that "drunk" look. However, her neurologic signs were constantly changing.

"I figured it was rabies, EEE (Eastern equine encephalitis), WEE (Western equine encephalitis), or West Nile virus," said Slovis. He ran tests for all of the encephalitis viruses, and even took a spinal tap to rule out EPM.

Slovis said the filly was in the clinic for three days, and each day her neurologic signs would change. First she was ataxic and had the "shakes" or muscle tremors in her neck, face, and thorax. Any movement caused the tremors to commence. Her depth perception was affected as well. "She'd go for her water bucket and miss by five inches," he said.

On the second day she was hypersensitive to touch. "If you barely touched her, she acted like she'd been stung," Slovis said. "She also was depressed."

By the third day, the shaking had disappeared by 90%, but her muzzle deviated and her neck was bent to the right. She had an unusually high gait with her front legs when she tried to move.

Slovis began treating the filly with DMSO and fluids twice a day, and a course of treatment that included dexamethasone, vitamin E, and banamine.

All of her blood work was normal, but she had twice the normal protein counts in her cerebrospinal fluid, said Slovis. "That is indicative of inflammation in the central nervous system."

The horse is now home and recovering.

About the Author

Stephanie L. Church, Editor-in-Chief

Stephanie L. Church, Editor-in-Chief, received a B.A. in Journalism and Equestrian Studies from Averett College in Danville, Virginia. A Pony Club and 4-H graduate, her background is in eventing, and she is schooling her recently retired Thoroughbred racehorse, Happy, toward a career in that discipline. She also enjoys traveling, photography, cycling, and cooking in her free time.

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