20. Cesky Terrier
Originating in Czechoslovakia, this breed is considered to be one of the rarest breeds in the world. This dog was brought to the USA in the 1980s, but the domestication of this dog breed is near-to impossible due to the strict grooming needs and the ability of the dog to shed in large amounts. While this dog might make a great show dog, it is not a breed that people own anymore.