Reduced Dewormer Efficacy & Need for More Targeted Treatment
Farmers often use a treatment called fenbendazole to deworm goats and sheep. These internal parasite infections, if not treated, can compromise the animals’ health and ultimately cause death. Deworming helps prevent economic losses for farmers by maintaining animal productivity.
Prior to this study, the prevalence of fenbendazole resistance in southern New England sheep and goats was unknown. This study is the first step in supporting farmers by equipping them with actionable information on treatments that do not protect their herds.
Testing for Efficacy
Dr. Eleanor L. Kharasch, a 2023 FFAR Veterinary Student Research Fellow, sampled parasitic fecal egg counts in sheep and goats to evaluate fenbendazole’s effectiveness. Kharasch and a Cummings School of Veterinary Medicine at Tufts University research team conducted fecal egg count reduction tests on 110 sheep and goats from 19 farms in Connecticut, Massachusetts and Rhode Island.
Researchers measured parasite levels before and after treatment using fecal egg count reduction tests and found that the drug often failed to control infections. The research team also surveyed local farmers to learn about their parasite management practices including their use of fenbendazole.
Accurately Testing Parasites
The research confirmed that parasites in sheep and goats across southern New England are currently largely resistant to fenbendazole. Researchers learned that moving animals between farms was not linked to changes in fenbendazole’s effectiveness. The research also revealed that testing for parasites in early summer, when parasite levels naturally begin to rise, provides a more accurate picture than testing in spring, when levels are still low. Accurate test results help farmers treat animals before they become seriously ill or die and ensure that only animals who need antibiotic treatment receive it.
Additionally, a southern New England farmer survey highlighted the need for accurate animal weighing and better use of parasite management tools, especially given the region’s limited pasture space.
This study’s regional-specific data can advance parasite management on a larger scale, reduce the use of unnecessary treatment and slow rates of resistance to medically necessary drugs in sheep and goats. It can also provide U.S. farmers in other regions with valuable insights to make better parasite-control decisions on their own farms.
This project was supported by the Foundation for Food & Agriculture Research, Cummings School of Veterinary Medicine at Tufts University and the Tufts Jonathan M. Tisch College of Civic Life for student research.