
Australian Shepherds are supposed to have full dentition: 42 teeth including three incisors, one canine, and for premolars on each side of each jaw, with two molars on each side of the upper jaw and three on the lower as seen in the chart at right (click to make larger).
The Australian Shepherd is a breed with functional heritage and many of them still perform useful work. While a single missing tooth may be a small matter, multiple missing teeth are anything but functional. Missing teeth are inherited.