A mutt is a dog with parents from different breeds, possibly also mutts. The term is sometimes used informally to refer to mixed breeding of other species as well. Mutts can be of two types:
- A mix of otherwise well recognized breeds, such as a shepherd-collie cross. Many popular breeds today, such as the golden retriever, resulted from such cross-breeding. Popular cross-breeds today include the pekeapoo, a cross of the Pekinese and the poodle.
- The basic canis familiaris. If dogs breed indiscriminately for many generations, the result is a short-haired brown dog of about 40 pounds (18 kg). All modern breeds of dogs are the ancestors of such mutts.