Toy Breed: A classification of dog breeds that are very small in size, typically weighing less than 7 pounds, and bred primarily as companion animals.
Brachycephalic: A term used to describe dogs with a shortened, flattened skull and muzzle, which is a characteristic feature of Chihuahuas and other toy breeds.
Kennel Club: An organization that sets breed standards and maintains pedigree records for purebred dogs, including the American Kennel Club which recognizes the Chihuahua as a distinct breed.