SCOPS warns about closantel overdosing
An overdose of closantel can cause blindness in sheep.
Sheep farmers need to be careful when using flukicides and wormers which contain closantel, the Sustainable Control of Parasites in Sheep (SCOPS) group has warned.
Closantel, an active ingredient in a range of antiparasitic products, is safe to use when the label instructions are followed and animals are dosed according to their weight.
However, SCOPS has reported that it has been made aware of a few recent cases in which sheep have received an overdose of the drug, causing blindness for the animals involved.
SCOPS spokesperson Lesley Stubbings said: “Because of the risks posed by overdosing with closantel, SCOPS urges sheep farmers to split a group if the weight variation is large, grouping sheep into weight bands and altering the dose rate accordingly. That is safer than dosing to the heaviest animal and administering too much closantel to small animals.
“Closantel is an important active in the control of internal parasites. This isn’t a recommendation to avoid the product – just a reminder of the risks of not weighing animals and giving them too much.”
Any farmers or veterinary professionals who see an adverse reaction to closantel in sheep are urged by SCOPS to report it to the Veterinary Medicines Directorate.
The BSAVA has opened submissions for the BSAVA Clinical Research Abstracts 2026.
