In other species: domestic cat , pig , llama , white-tailed deer , taurine cattle , goat , sheep , alpaca

Categories: Skeleton phene (incl. short stature & teeth) , Craniofacial phene

Mendelian trait/disorder: unknown

Disease-related: yes

Cross-species summary: Congenital abnormal shortness of the maxilla (upper jaw), resulting in protrusion of the mandible (lower jaw).

Species-specific name: maxillary brachygnathism, congenital malocclusion, mandibular prognathism, crossbite

Species-specific description: Disproportions in jaw length between upper and lower jaw result in teeth that are not positioned correctly and to dental malocclusion. Brachygnathia superior is observed in rabbits, most frequently in dwarf breeds.

History: Nachtheim (1937) first described brachygnathia superior in rabbits and his findings were cited by Robinson (1958, pp342-343).

Inheritance: Nachtheim (1937) suggested a recessive mode of inheritance. Huang et al. (1981) proposed a "simple autosomal recessive inheritance with incomplete penetrance for this condition". Korn et al. (2016) estimated heritability to be 25%.

Clinical features: In rabbits, teeth grow throughout their life. Rabbits with brachygnathia superior can have severely overgrown teeth due to abnormal wear. This can result in difficulties to feed and groom and associated severe health problems (Harcourt-Brown 1997, 2009). Affected animals require regular veterinary treatment.