Risk of dewormer resistance
A study has revealed that horse owners are largely unaware that there is a threat of resistance to dewormers and, therefore, do not know the importance of "targeted" dosing.
Published in the Equine Veterinary Journal (EVJ), the questionnaire-based study revealed that horse owners are using faecal worm egg counts (FWEC) more frequently and are increasingly looking to vets for worm control advice.
It found that, of 193 questionnaire responses revealing the parasite control programmes of 993 horses, 86 per cent were unaware of the presence of resistance on their yard.
Furthermore, the majority scored resistance to dewormers at an importance of just six out of 10 – with 10 being the highest level of concern.
There are currently three classes of anthelmintic available against small redworm – the equine gastrointestinal worm that brings greatest concern, due to its high prevalence and potential to cause life-threatening disease.
Of those three classes, there is now widespread resistance to benzimidazoles and tetrahydropyrimidines, as well as reduced effectiveness of macrocyclic lactones.
The study's collaborators have said that, in order to preserve the efficacy of dewormers, further effort is needed to help owners fully understand the issues associated with them.
"It's very encouraging to see that vet advice is being increasingly sought and it seems logical that the use of FWECs is increasing accordingly," said Professor Celia Marr, editor of EVJ.
"But it is equally important that the information gained from the FWECs is used wisely. Resistance to dewormers is a major health concern that is with us right now and horse owners need to be made more aware of it."
The study was conducted by Horse Trust's clinical scholar in equine medicine at the Royal (Dick) School of Veterinary Studies, the University of Edinburgh and Moredun Research Institute.
BSAVA is to partner with BVA Live (11-12 June 2026) to champion clinical research.
