Drenching or bolusing sheep should be done to improve the health and welfare of an animal but done incorrectly it can cause severe injuries, according to David Harwood, AHVLA vet investigation ...

He explained that if a rancher had 500 cattle roaming across grazing tracks all of the boluses would be networked together and this allows data to jump from one animal to another.

More than 270 cases of severe throat injuries in sheep following use of a drenching/bolus gun have been identified by the Veterinary Laboratories Agency in England and Wales over the past 10 years.