Time and sequence of emergence of the deciduous dentition in dogs and its applicability for age estimation

This study investigated the influence of several covariates on the time and sequence of deciduous dentition emergence in puppies. Data were obtained in a longitudinal study, with some cross-sectional observations, of 1001 puppies of 53 dog breeds. A parametric proportional hazards survival model was used to estimate median emergence time and evaluate the effect of the covariates. No significant differences were found between the left and right sides of a puppy's dentition, but differences were statistically significant for the earlier appearance of maxillary incisors and canines and later appearance of maxillary premolars compared with their mandibular counterparts. The tendency for delayed onset and completion of emergence in female compared to male puppies was statistically but not clinically significant. The differences between puppies of breeds of different size or skull type were both statistically and clinically significant, with small and brachycephalic breeds showing later emergence times, longer clinical eruption times and more individual variation. Per quadrant, regardless of dog breed, canines or incisors were usually the first teeth to emerge and fully erupt, followed by premolars in the order Pd3 > 4 > 2. The maxillary canines and incisors usually emerged earlier than mandibular canines. Age estimation standards for breed size groups are presented based on the number of emerged teeth per quadrant. To assess whether a puppy has reached the legally required minimum age of 8 weeks to leave the litter, the best predictive capability using the data from this study is obtained when assessing the emergence status of the deciduous third premolars.