Sheep lice (biting and sucking) cause significant welfare harm through intense itching and wool damage. Control requires correct product selection and good biosecurity.
Louse infestation causes chronic welfare harm — the constant irritation of biting lice leads to excessive rubbing, fleece damage, and visible distress. Sucking lice cause blood loss that can contribute to anemia in heavily affected animals. Affected sheep spend more time scratching and rubbing and less time grazing. Treatment with appropriate insecticides rapidly resolves infestation and restores normal behavior. Biosecurity measures preventing introduction of infested stock are far preferable to treatment — lice-free flocks maintained through good quarantine practices avoid the welfare harm entirely.