A "sooner" dog could refer to a dog that is a mixed breed or one that is from Oklahoma. "Sooner" dogs are not a specific type of breed on their own. A "sooner" dog can also be used in reference to dogs that are not housebroken and will "sooner" go in the home than outside.
Many dogs are not purebred but are rather a mix of two or more breeds. These dogs are sometimes also referred to as "mutts" or "Heinz 57." Some dogs have been given new breed names that are a combination of the two parent breeds. For example, a Bogle is a Boxer and Beagle mix, while a Yorkie Poo is a Yorkie and Poodle mix.