Mysteries of Equine Herpesvirus-1 Shedding

While it's widely hypothesized that horses shed equine herpesvirus-1 (EHV-1) during times of stress and illness, researchers on a new study say that critically ill horses with acute gastrointestinal disease (colic or colitis) in a veterinary hospital do not appear to shed the virus.

According to Elizabeth Carr, DVM, PhD, Dipl. ACVIM, ACVECC, assistant professor in Michigan State University's Department of Large Animal Clinical Sciences at the College of Veterinary Medicine, EHV-1 is an important infectious disease in horses that can cause outbreaks of disease both on farms and in hospitals. Veterinarians seem to be diagnosing it more frequently.

"Once horses are infected, the virus lies dormant and can recrudesce (become active again) at any given point," explained Carr. "To date, the triggers that cause nasal shedding of EHV-1 remain unclear."

To assess the impact of stress and disease on nasal shedding of EHV-1, Carr and colleagues evaluated 122 hospitalized, critically ill horses older than six months of age. They tested horses' blood samples and nasal secretions for EHV-1 using a polymerase chain reaction test (a DNA test).

"Our results showed that not one of the hospitalized horses was positive for EHV-1, suggesting that shedding of EHV-1 is extremely rare in these cases," said Carr.

These data are anticipated to contribute to the body of knowledge veterinarians are amassing regarding infection control and biosecurity in veterinary hospitals.

Carr presented this data in her talk, "Equine herpesvirus-1 (EHV-1) recrudescence and viremia in hospitalized critically ill horses," at the American College of Veterinary Internal Medicine (ACVIM) Forum, held June 4-7 in San Antonio, Texas.

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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