Monday, October 14, 2013


A new study published earlier this month in the Veterinary Record1 has shown that targeting anthelmintic treatments to horses that have a high worm egg count in the faeces was more cost effective than the more traditional approach of interval treatments of all horses on a yard at the same time. A targeted approach will also help to increase the long term efficacy of the existing drugs by reducing the selection pressure for drug resistance.

The study, led by scientists at the Moredun Research Institute and involving collaboration with Bristol, Liverpool and Edinburgh Veterinary schools, involved 368 horses in 16 different yards across the UK. Faecal samples were screened for the presence of worm eggs in all horses enrolled in the study and on the basis of the results obtained only those horses with high counts were selected for worming treatment. The cost of this regime was compared with a more traditional approach of all horses in the yard being treated 4 times a year. The average annual saving of adopting the targeted treatment approach was around £300 per yard.

Hannah Lester, lead researcher on the project from Moredun, commented, "The frequent use of anthelmintics in horses has contributed to the development and spread of drug resistance in equine worm populations, which has lead to problems with the efficacy of treatments. This study has shown that if we target the treatment to the horses that actually need it we will help to reduce the development of drug resistant parasite populations and save money too."

Currently, worm infections in horses are treated using three different classes of broad spectrum anthelmintics and with no new drugs likely to be licensed for use in horses in the foreseeable future it is essential to preserve the efficacy of the existing drugs for as long as possible.

Professor Jacqui Matthews, Deputy Director, Moredun, said. "We hope that the results from this study will encourage horse owners to adopt a new strategy of targeted worming treatment for their horses as there are real economic and efficacy benefits from doing so."

1H.E. Lester et al (2013) A cost comparison of faecal egg count - directed anthelmintic delivery versus interval programme treatments in horses. Veterinary Record .

The authors of the study are grateful for support received from The Horse Trust and Hannah Lester's PhD scholarship was funded by the Elise Pilkington Trust.



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