From the Colorado State Veterinarian's Office

Five equine cases of West Nile Virus (WNV) have been diagnosed in Colorado as of August 14th, 2012

Five equine cases of West Nile Virus (WNV) have been diagnosed in Colorado as of August 14th, 2012. The WNV positive horses are from Fremont, Weld, Montrose (2), and Larimer counties.

The incidence of the disease varies from year to year and depends on a number of factors, including mosquito numbers. The West Nile virus can be carried by infected birds and then spread locally by mosquitoes that bite those birds. The mosquitoes can then pass the virus to humans and animals.

Infected horses may display symptoms including head tilt, muscle tremors, stumbling, lack of coordination, weakness of the limbs or partial paralysis. If horses exhibit clinical signs consistent with WNV, it is very important for horse owners to contact their veterinarian in order to confirm the diagnosis through laboratory testing. Horse owners should consult their private practicing veterinarian to determine an appropriate prevention strategy for their horses.

Vaccines have proven to be a very effective prevention tool and we need to continue to educate horse owners on the importance of WNV vaccination. Our veterinary staff at the State Veterinarian’s Office has done a very limited and informal survey of WNV vaccine sales in Colorado; it indicates a significant drop in vaccine sales over the past years. If this small survey is indicative of the overall sales, it is a disturbing trend. Of the five horses that have been WNV-positive, we have not been able to confirm that any of the horses have been vaccinated for WNV.

In addition to vaccinations, horse owners also need to reduce the mosquito populations and their possible breeding areas. Recommendations include removing stagnant water sources, keeping animals inside during the bugs’ feeding times, which are typically early in the morning and evening, and using mosquito repellents.
For more information concerning new WNV equine case information including numbers and location of test positive horses visit:
http://www.fightthebitecolorado.com/
http://www.cdphe.state.co.us/dc/zoonosis/wnv/

“It is important to protect your horse through WNV vaccination and good management practices, West Nile virus is a disease that threatens the health of humans, horses, and other animals. This is the time of year when we are most likely to see WNV cases reported in horses,” said Colorado State Veterinarian, Dr. Keith Roehr. “It is difficult to project how many WNV cases we may see in the coming months.”