A fatal gastrointestinal disease once limited to Scotland is being seen more frequently in certain parts of the world due to geographical progression, said British researchers.

Frequently occurring throughout Great Britain, equine grass sickness (EGS) has been detected in many countries in Europe and has even been confirmed in isolated cases in Africa and the United States. The "mal seco" disease in South America is generally considered to be EGS as well. Prognosis for EGS is usually poor.

Horse with Equine Grass Sickness

The chronic form of equine grass sickness causes sudden extreme weight loss leading to a "wasp waist" appearance.

A comprehensive clinical guide for detecting and treating EGS was recently published in Veterinary Clinics of North America in order to increase awareness of the disease on that continent, according to authors Claire E. Wylie, BVM&S, MSc, MRCVS, researcher in epidemiology and disease surveillance at the Animal Health Trust in Suffolk, and Chris J. Proudman, MA, VetMB, PhD, Cert EO, FRCVS, Chair in Equine Studies, Head of Department of Animal Health and Welfare, University of Liverpool. Until then, EGS had been "virtually unheard of in North America," Wylie said.

"We hope to highlight the importance of the condition, which is known to affect horses recently moved on to new pastures," she said. "(Our publication) gives advice for veterinarians and owners involved in moving horses into high-risk areas."

High-risk areas are pastures where other horses have become ill with EGS, Wylie said. The disease is not transmissible from horse to horse and does not appear to be transferred via insects or any other vector. No particular toxins or deficiencies appear to be related to the onset of EGS. "The risk seems to be associated with a causal agent in the environment of certain grazing areas," she said. "Unfortunately that agent has yet to be identified."

A vaccine is currently in development based on a theory that EGS might be related to a botulism toxin, according to Wylie.

In the acute form of EGS, horses usually experience colic, loss of appetite, and excessive salivation. Death invariably occurs within a week. The chronic form causes sudden extreme weight loss leading to a "wasp waist" appearance. Only mild cases of this chronic type have a chance for recovery, the researchers reported.

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at home near Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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