Skull size and cheek-tooth length in wild-caught and captive-bred chinchillas

Chinchillas are herbivorous rodents with teeth that all grow continuously. In captivity, they are commonly affected by dental disease. As the range of dental disease occurring in wild chinchillas is unknown, the dentition of museum specimens originally obtained from the wild was assessed and compared with specimens prepared from captive-bred animals. Skulls from wild-caught chinchillas showed minimal evidence of dental disease and the teeth were all short, cheek-tooth lengths averaging 5.9 mm. Cheek-tooth lengths in zoo specimens (average 6.6 mm), clinically normal (average 7.4 mm) and captive-bred animals with dental disease (average 10 mm) were significantly elongated by comparison (P<0.0001). Captive-bred specimens showed a wide range of tooth-related lesions. These results suggest that some aspect of captivity is responsible for the development of dental disease in chinchillas. It is suggested that the diet (its physical form and composition) is the main aetiological factor, and that provision of a diet closely matching that of wild chinchillas should significantly reduce the incidence of dental disease in captive animals.