Researchers at the University of Kentucky’s Gluck Equine Research Center recently completed a 40-year investigation of drug-resistant small strongyles in horses. E.T. “Gene” Lyons, PhD, a researcher at Gluck, said the study offered information that could help horse owners and clinicians better understand parasitism in horses. The study was published in the July issue of Parasitology Research.

Lyons said, “The information from this study is unique because of accurate records kept over an almost 40-year period on antiparasitic compounds used and frequency of usage. The purpose of the data was mainly to provide (quantification of) the prevalence of internal parasites in horses of known age in a closed herd, without antiparasitic usage for many years.”

The study included 14 horses ranging from 239 days old to 23 years old housed on two separate lots. Lyons said it had been 26 years since the horses in one lot had been given any type of dewormer and nine years since the other lot’s horses had received anthelmintic treatment