Small dogs can be adopted for free from dog adoption and rescue centers. Online services such as Pet Finder list dogs by breed, allowing users to search for small breeds. Some small dog breeds include the Brussels Griffon and Cavalier King Charles Spaniel, notes the American Kennel Club.
Pet Finder's list of dogs for adoption shows how many of each breed is currently available for adoption. Clicking this will show the location of each dog.
Adopt a Pet.com is another site offering small dogs for adoption. It has a small dog search engine which sorts available dogs by type, color, sex, age and location.