There is no such thing as a Shetland and sheepdog mix. The Shetland sheepdog is a purebred dog recognized by the American Kennel Club. The Shetland sheepdog was originally bred in the Shetland Islands in Scotland to stand guard to keep birds and sheep out of farmers' gardens.
The Shetland sheepdog stands 12 to 16 inches tall and weighs an average of 20 pounds at maturity. They have a life expectancy of 12 to 15 years. The Shetland sheepdog is intelligent and loyal and makes an excellent family pet. Shelties are not aggressive, but they are very vocal. Their coats are long, which means they shed a lot.