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K-State vets care for horses with West Nile, prepare for next season

By Michelle Hall

 

In a matter of weeks in late summer 2002, the equine internal medicine veterinarians at Kansas State University's Veterinary Medical Teaching Hospital became authorities on caring for horses with the West Nile virus.

They had to -- more than 50 horses were hospitalized at K-State with the virus over a period of three months.

"We saw our first case in early August," said Dr. Bonnie Rush, professor of equine internal medicine. "Before, we'd never even seen a case. Now we're experts."

They prepared for the onset of the virus in Kansas, Rush said, as the mosquito-borne illness, introduced into the United States on the East Coast in 1999, spread west. Rush spoke to the Kansas Legislature to inform them of the impending arrival of the virus, provided information to the media to inform the public and invited an equine internal medicine specialist from the University of Florida to lecture to the faculty, staff, students and horse owners regarding her experience with the disease.

But it still wasn't easy figuring out how to treat the virus when it did arrive. West Nile causes encephalitis, or swelling of the brain. When horses are affected by the virus, they become weak and disoriented. There is no cure for West Nile, although there is an effective vaccine.

"Although it's not hard to diagnose, it is a disease that is unpredictable in its course," Rush said. Treatment included supportive care and medications to fight the virus and, most importantly, to reduce the inflammation in the brain.

"We learned quickly what works and doesn't," Rush said. "It was a big challenge but very important to keep the horses sedated. We also adjusted the dosage of Interferon (the anti-viral medication), until we found what worked best." In addition, they decided to replace the padding in the horses' stalls with thicker material -- horses with the West Nile virus often press their heads against the walls for support as their muscles twitch or they become weak and disoriented.

Although the horses are severely incapacitated for days as the virus runs its course, the good news is that most of the horses Rush saw are back to their pastures or pens now.

"The vast majority that survive do great," Rush said. "It's hard to imagine, when you see them at their worst, that they can get better. That's the encouraging thing about this disease -- affected horses have a good chance for a good recovery."

The horses Rush and her colleagues cared for had a nearly 85-percent survival rate, while the national average is only about 70 percent.

Dr. Roger Fingland, professor of surgery and director of the teaching hospital, said he is as proud of the doctors and students who cared for these horses as he has ever been of any group at the hospital.

"Few people, including the clients, will ever have an appreciation for the amount of work our doctors, students, residents and interns put in with these horses," Fingland said. "It's nothing short of amazing what these people did. The amount of care these horses require is phenomenal."

Fingland said some of the horses even had to be catheterized or have stomach tubes put in.

"These horses literally could not do anything and our clinicians and students did everything for them," he said. "Many, many horses are alive today that wouldn't be if not for the people in this hospital."

Rush anticipates the same number of patients this summer and fall as the mosquitoes return and the virus hits the state yet again. She said Florida, for example, saw about the same number of cases of the virus the second year as in the first year after the virus arrived in the state.

Rush highly recommends horse owners have their animals vaccinated in the spring and re-vaccinated in July. The peak of West Nile season is in September. And if owners suspect their horse is showing signs of the virus, Rush asks them to send a blood sample in to the diagnostic laboratory at K-State -- that's the only way, she said, to document the number of cases in Kansas.

Photo of vaccination

Frank Purling, Hereford, Texas, steadies his horse Mariah while student Solene Moreton administers a West Nile virus vaccination.

Spring 2003