Sheep scab is a contagious, highly pruritic disease caused by the mite Psoroptes ovis. Affected sheep develop large, yellowish, scaly, crusted lesions, accompanied by damage to the wool and hide. Emaciation and secondary bacterial infections can occur in untreated animals, pregnant sheep give birth to smaller lambs, and lambs that become infested may lose condition rapidly and die. Sheep scab is an animal welfare concern due to the pain and irritation caused by the mites.