The standard of 42 teeth is normal for all adult dogs, whether large or small. An exception is the hairless breeds, such as the Chinese Crested, because the hairless gene also modifies dentition. And in Bulldogs and other bracycephalic breeds, the last molars may be absent because of the short jaw.
Some dogs carry a genetic mutation for missing teeth. Doberman Pinschers may have fewer than the normal eight premolars. This is considered a show fault but has no real significance in terms of the dog’s health, unless the missing teeth shift the bite. Genetic variations of this type usually are hereditary.
You may find that your dog has more teeth than normal. This occurs most often in spaniels and sighthounds (especially Greyhounds). The extra teeth may crowd, twist, or overlap the normal teeth. The offending teeth should be removed.