A pit bull can mate with a chihuahua. The resulting puppies, sometimes called pithuahuas or chipits, are available from designer dog breeders. According to Pet Your Dog, chipits average anywhere from 15 to 45 pounds when fully grown and are active, lively and loyal.
All dogs, no matter what the breed, are members of the species Canis lupus familiaris. Scientists consider the dog to be a subspecies of the gray wolf. Selective breeding by humans is responsible for the remarkable number and variety of different breeds. Regardless of their size and appearance, all dogs are theoretically capable of interbreeding and producing offspring.