Which breed of dog is this?

The Shetland Sheepdog, often known as the Sheltie, is a breed of herding dog that originated in the Shetland Islands of Scotland. The original name was Shetland Collie, but this caused controversy among the Rough Collie breeders of the time, so the breed's name was formally changed.

This hard-working small dog is intelligent, vocal, excitable and willing to please. They are incredibly loyal to their owners to the point where they are often referred to as "shadows" due to their attachment to family. This breed was formally recognized by The Kennel Club (UK) in 1909.

Like the Shetland pony, Shetland Cattle and the Shetland sheep, the Shetland Sheepdog is a hardy but diminutive breed developed to thrive amidst the harsh and meagre conditions of its native islands. While the Sheltie still excels at herding, today it is often raised as a farm dog and/or family pet.

Shelties normally weigh around 5–11 kilograms (11–24 lb). In general, males are taller and heavier than females. Accepted height ranges may differ depending on country and standard used.

Shelties have a high level of intelligence. According to Dr Stanley Coren, an expert on animal intelligence, the Shetland sheepdog is one of the brightest dogs, ranking 6th out of 138 breeds.

Shelties can also be great therapy dogs for those who need comfort during hard times such as natural disasters or severe illness. This breed is rarely aggressive and tends to do well with children and being handled by them.