Temporomandibular joint morphology in Cavalier King Charles Spaniels

Temporomandibular joint dysplasia has been reported in several breeds of dog. Three Cavalier King Charles Spaniel (CKCS) skulls were examined and radiographed during the course of a separate study and all demonstrated changes consistent with bilateral temporomandibular joint dysplasia. Subsequently, skull radiographs from all CKCS dogs examined at the University of Glasgow Veterinary School between 1991 and 2001 were reviewed (n = 26). Only two of these dogs were radiographed specifically for investigation of the temporomandibular joint, although varying degrees of dysplasia were identified in all dogs where the joints were adequately visualized (n = 20). The head of four CKCS cadavers was also radiographed, and similar changes were found. This finding suggests that temporomandibular joint dysplasia is a widespread asymptomatic condition in the CKCS and should be regarded as a normal morphologic variation rather than a pathologic anomaly. Subtle changes are best seen on lateral oblique radiographs, although marked changes are also visible on dorsoventral views. The rotational angle or angle of articulation of each of the dysplastic mandibular condyles was measured and was related to the severity of the dysplastic changes. However, there was overlap between the values calculated for these abnormal joints and normal ones in other breeds, suggesting this measurement was of limited significance and the shape of the components of the temporomandibular joint are more relevant when assessing this joint for the presence of dysplastic changes.