In this study, dogs between 8 and 12 weeks of age were examined to evaluate occlusion. Dogs were categorized as either individuals or members of a litter and further classified as purebred or crossbreed. Occlusions were evaluated by class and level of severity. Of the 297 dogs in the study population, 25.9% were identified as having malocclusion. Individual purebred dogs had a significantly higher percentage (33.8%) of malocclusion as compared with individual crossbreed dogs (20%). For dogs in litters, no purebred dogs were noted to have malocclusion, but 23.5% of crossbreed dogs in litters were presented with malocclusion. When all groups were combined, there was no significant difference in prevalence of malocclusion between crossbreed and purebred dogs.
Malocclusions in dogs can vary in severity and are classified based on the relationship of the maxilla and mandible. Class I malocclusion indicates a normal jaw relationship, but individual teeth may be malpositioned. Class II malocclusion describes occlusion in which the mandible is distal in position to the maxilla (ie, mandibular distocclusion). Class III malocclusion describes occlusion in which the maxilla is distal in position to the mandible (ie, maxillary distocclusion)1; this particular malocclusion may be considered normal in some American Kennel Club breeds (eg, brachycephalic dogs). Malocclusions in dogs are common and can develop into significant patient morbidity if left untreated. The length of the mandibular canines can be problematic in malocclusion, and oronasal communication can develop from chronic abnormal contact of the mandibular canines with the maxillary hard and soft tissue.