Towards a scientific standard of dentition

Dog breed standards provide a description of the facial region, with details on muzzle and teeth. However, there is significant variability in details provided, e.g. according to the breed’s country of origin, and in the tolerance to deviations from a complete dentition. In light of this, we evaluated 341 dog breed standards approved by the Fédération Cynologique Internationale (FCI). The cranio-facial ratio was absent in 31% of the standards, including many brachycephalic breeds. By contrast, almost all breeds in Group 1 (Sheepdogs and Cattledogs) included this information. Groups 2 (Molosses, Pinscher, and Schnauzer) and 9 (Companion and Toy Dogs) displayed the greatest variability and the lowest average ratios, whereas Group 6 (Scent Hounds) and 10 (Sighthounds) were more homogeneous, with predominantly meso-dolichocephalic breeds. Scissor bite was accepted in 93% of the breeds and considered a disqualifying fault in only 6%. However, 13% of Group 2 and 38% of Group 9 preferred an undershot bite. PM1 and M3 were the most tolerated missing teeth, being allowed in 18% and 13% of the standards, respectively. Groups 1, 7 (Pointing dogs), and 4 (Dachshunds) were the most permissive regarding dental agenesis. Conversely, no breeds in Group 8 (Retrievers, Flushing, and Water Dogs) allowed missing teeth. The lack of scientific data on dental agenesis in dogs limits the ability to define breed standards objectively. Studies comparing the prevalence of missing teeth across breeds and mixed-breed dogs are necessary to determine whether this trait represents a genetic defect or an evolutionary adaptation to domestication and dietary changes. Such studies could also justify different levels of tolerance across breeds or groups. In conclusion, significant variability exists among dog breed standards in describing dentition and muzzle conformation and, in the context of conformation dog shows, judges often interpret these traits inconsistently across breeds and countries. A harmonized collection of data and evaluations and a more uniform and scientific approach to defining breed standards are essential for ensuring a fair and welfare-oriented canine evaluation.