Study: Light-Colored Horses at Higher Risk of Dying from West Nile Virus

Researchers at the Western College of Veterinary Medicine in Saskatchewan, Canada, recently published a study indicating that light-colored horses diagnosed with West Nile virus (WNV) might be more likely to succumb to the disease than their darker counterparts.

Horses included in the study were divided into three groups based on coat color: dark (chestnut, bay, black, brown, and sorrel), light (gray, white, palomino, buckskin, and dun), or multicolored (roan, paint, pinto, and appaloosa).

Of the 124 horses diagnosed with WNV grouped according to coat color, dark-colored horses were most commonly infected (89 out of 124 cases, or 71.8%). However, the fatality rate was only 36% in the dark group, compared to 74% in light-colored horses.

"Our study found that light-colored horses were 4.4 times more likely to die or be euthanized than dark-colored horses," reported Tasha Epp, DVM, a co-author on this study.

There reason for this remains unknown, but the researchers suggested that immune response in horses might be genetically linked to coat color.

The study, "Factors associated with West Nile virus disease fatalities in horses," was published in the Canadian Veterinary Journal in November 2007. For more information on this study see  

About the Author

Stacey Oke, DVM, MSc

Stacey Oke, MSc, DVM, is a practicing veterinarian and freelance medical writer and editor. She is interested in both large and small animals, as well as complementary and alternative medicine. Since 2005, she's worked as a research consultant for nutritional supplement companies, assisted physicians and veterinarians in publishing research articles and textbooks, and written for a number of educational magazines and websites.

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