A deer head Chihuahua is a type of Chihuahua that has a longer snout than the apple head version of the breed and suffers fewer health problems. His narrower skull is reminiscent of that of a deer, thus the reason for the moniker.
The American Kennel Club does not recognize the apple head or deer head as separate varieties of the breed, and neither do any similar organizations. The organizations, however, do discriminate between the two, holding the apple head as the standard bearer.
The apple head has a rounder head and a shorter muzzle. His forehead and jawline are more prominent than those of the deer Chihuahua.