With rare exceptions, puppies are born without teeth. The first teeth to erupt are the incisors, at 2 to 3 weeks of age. Next are the canines and premolars. The last premolar erupts at about 8 to 12 weeks of age. As a rule, the teeth of larger breeds erupt sooner than those of smaller dog breeds.
The average puppy has 28 deciduous (temporary or baby) teeth. These are the incisors, canines, and premolars. Puppies don’t have molars.
The deciduous teeth remain for only three to seven months. Beginning at about 3 months of age, the baby incisors are shed and replaced by adult incisors. By 5 months, a puppy should have all her adult incisors. The adult canines, premolars, and molars come in between 4 and 7 months of age. Thus, by 7 to 8 months of age, a puppy should have all her adult teeth. Knowing this teething sequence can give you an approximate idea of the age of a puppy.
The average adult dog has 42 teeth: 22 in the mandible or lower jaw, and 20 in the maxilla or upper jaw. In each jaw there are 6 incisors, 2 canines, and 8 premolars. There are 6 molars in the lower jaw and 4 in the upper jaw. The wear on the incisors is used to judge the age of the adult dog.
How Dogs’ Teeth Reveal Their Age
In adult dogs, approximate age can be determined by checking the wear on the incisors. This method is relatively reliable up to about 6 years of age, but individual variations do occur. Beyond 7 years, using the teeth to determine age is unreliable.
The edges of the incisors are called the cusps. The amount of wear on the cusps is the most important factor in determining the age of the dog. The chart on 241 explains how wear patterns typically occur (upper and lower incisors are identified by numbers, as shown in the figure on this page). Wear patterns are described for each age, but individual variations do occur. Dogs who chew on metal, such as crate or fence wires, or chew on abrasive materials such as tennis ball coverings, will wear down their teeth more quickly.