What is a male dog called?

A male dog is simply referred to as a "dog." The use of the word specifically for a male dog is correct according to the American Kennel Club, even though this is also the term for the species as a whole.

Other words are used to describe male dogs in certain circumstances. For example, an adult male dog who is used as a breeder is a "stud." A male dog that is the father of a litter of puppies is a "sire." Any dog under the age of 12 months is called a puppy, regardless of whether the animal is male or female.