Tracheitis in sheep after oral administration of a mineral supplement

Outbreaks of illness and deaths in sheep after the concurrent administration of a cobalt, copper and zinc mineral supplement and laevamisole are described. Clinical illness was characterised by profound dyspnoea and inability to exercise. The consistent postmortem finding was severe, necrotising tracheitis with partial occlusion of the airway. This lesion was reproduced experimentally by intratracheal administration of the mineral supplement dissolved in one particular formulation of laevamisole but not in water or another preparation of laevamisole. Further experiments revealed that combined zinc sulphate and copper sulphate dissolved in the particular formulation of laevamisole would produce the tracheal lesions.