Aberrations of the tooth arcade and mandible in Dall's sheep from southwestern Yukon.

Nine Dall's sheep (Ovis dalli dalli) collected in the Ruby Mountains of southwestern Yukon were examined for aberrations of the tooth arcade and mandible. Missing and displaced teeth were common in older sheep (greater than or equal to 6 yr). Necrosis of the mandible was observed in five of eight rams and in one ewe. Corynebacterium pyogenes was cultured from exudates from two rams with enlarged fistulated mandibles. The sequence of events leading to lesions of the tooth arcade and to "lumpy jaw" is postulated to be associated with abnormal wearing of teeth and a disrupted alignment of the tooth arcade, impaction of vegetable matter between teeth and between the gingiva and the root of the tooth, and penetration of the traumatized gingiva membrane and alveolus by oral bacteria which induce a necrotizing infection.