Is Your Dog a Mixed Breed by Design or by Accident?

If you can't decide between a shepherd, a setter or a poodle, get them all — adopt a mutt.

http://www.dogbreedinfo.com/mixbreed/mutt.htm

Mixed-breed dogs vary tremendously in looks, size and temperament, even varying within the same litter. A mixed-breed dog is a dog that is not a purebred; also called a mongrel, or mutt. Mongrels and mutts are technically dogs of unknown ancestry and questionable parentage.

A hybrid, on the other hand, is a dog that is not purebred, but whose ancestry is known. For example, a Poodle bred to a Golden Retriever is called a Goldendoodle and is considered a hybrid or crossbreed.

Scientifically speaking, the term "hybrid" is incorrect as all dogs are a sub-species of wolf (canis lupus familiaris) and as such, it is impossible to have a hybrid as they are two of the same species.