A miniature cocker spaniel is a crossbreed between a purebred cocker spaniel and a purebred toy breed that produces miniature-sized puppies. There are several toy breeds used; perhaps the most common is an English cocker spaniel mixed with an English toy spaniel, according to the Dog Breeding Info Center.
As miniature cocker spaniels are not a recognized breed, anyone claiming to sell purebred miniature cocker spaniel puppies is obscuring their actual origin. However, multi-generational crosses are common with this hybrid variety. Another source of confusion is that English toy spaniels are sometimes incorrectly called toy cocker spaniels. They are, in fact, entirely separate breeds with different standards and lineages.