Lumpy jaw in wild sheep and its evolutionary implications

The distribution and prevalence of mandibular osteomyelitis, lumpy jaw, and other dental anomalies in wild sheep were investigated and their biologica l and evolutionary implications were assessed. Our survey was based on 3,36 3 mandibles of wild sheep and 1,028 from domesticated varieties. Lumpy jaw is widespread in wild sheep of North America, but it is rare or absent in w ild sheep from Eurasia. Among the subspecies of Ovis spp. in North American , the thinhorn sheep (Ovis dalli) were the most seriously impacted, with a prevalence in Dall's sheep (O. dalli dalli) of 23.3% and 29.3% in Stone's s heep (O. dalli stonei). Among the bighorns (O. canadensis), the Rocky Mount ain subspecies (O. canadensis canadensis) had a higher rate (12.1%) than ot her subspecies. Lumpy jaw was not documented in the desert sheep of Baja Ca lifornia (O. canadensis cremnobates, O, canadensis weamsii). Based on data from affected thinhorn sheep, it appears there is an inverse relationship b etween age of a subspecies in a long term evolutionary context and suscepti bility to lumpy jaw. In Eurasian wild sheep lumpy jaw is rare or absent wit h prevalences ranging from O to 7.1% among suspecies, and in domesticated b reeds the prevalence averaged 5.0%. The impact of lumpy jaw on different ag e classes or longevity is equivocal, although females are more susceptible than males. Lumpy jaw appears to effect horn development in males.