Oesophageal injury associated with the administration of an anthelmintic bolus to calves.

Six of 18 calves from a suckler herd which were dosed with a sustained-release anthelmintic bolus, using appropriate equipment, developed clinical signs related to oesophageal perforation. Two died as a direct result of the injuries sustained, one required surgical removal of the paraoesophageal bolus and the remaining three were managed medically. The calves were in the approximate weight range advised by the manufacturers as suitable for dosing, but some were younger than the minimum recommended age. These animals were of a fractious nature having been relatively little handed.