Shetland Sheepdog: Size, Colours, Lifespan and Genetics
The Sheltie is a small herding dog from Scotland's Shetland Islands, and Canada's No. 10 breed. Here's its size, how sable, tricolour, bi-black and blue merle are inherited, what research found about lifespan, and the MDR1 drug-sensitivity variant.
By PuppyGenes · How we research and write our guides
The Shetland Sheepdog, or Sheltie, is a small herding dog from Scotland's Shetland Islands, and it was Canada's 10th most popular breed in 2025. It comes in sable, black or blue merle, marked with white and/or tan, and the merle gene was first mapped in this breed. In a UK Kennel Club survey, Shelties lived a median of about 11.3 years. About one in six Shelties in one study carried a variant of the MDR1 gene that can make dogs dangerously sensitive to some common drugs.
At a glance
| Trait | Shetland Sheepdog |
|---|---|
| Size | 33 to 41 cm at the shoulder; the AKC gives about 7 to 11 kg |
| Coat | A long, straight, harsh outer coat over a dense, furry undercoat |
| Colours | Black, blue merle or sable, marked with white and/or tan |
| CKC group | Herding |
| Origin | The Shetland Islands, Scotland; first shown at Crufts in 1906 |
| Median lifespan | About 11.3 years in a UK Kennel Club survey |
| Popularity | No. 10 in Canada, and No. 2 in Saskatchewan |
Not a miniature Collie
The CKC's breed page traces the Sheltie to the sparse Shetland Islands off Scotland's northeast coast, where small livestock suited small herding dogs. Its early ancestors may have included Spitz-type dogs similar to the Norwegian Buhund. Dogs taken to the mainland were crossed with toy breeds and small Collies, and they were first shown at Crufts in 1906 as the "Shetland Collie". Collie breeders objected, and the breed was renamed the Shetland Sheepdog. So the Sheltie has Collie in its history, but it's a breed of its own.
Today it's Canada's 10th most popular breed, second in Saskatchewan and fifth in Manitoba, as our list of the most popular dog breeds in Canada shows.
Sable, tricolour, bi-black and blue merle
Sheltie colours come from a few genes stacked together:
| Colour | Pattern genes |
|---|---|
| Sable | The sable version of the agouti gene: tan to mahogany hairs, often tipped with black |
| Tricolour | Black with tan points from the agouti gene, plus white markings |
| Bi-black | Recessive black from the agouti gene, plus white markings, with no tan |
| Blue merle | Merle on a tricolour dog |
| Bi-blue | Merle on a bi-black dog |
The sable version of the agouti gene was identified in a 2005 study from the University of Saskatchewan, which also found Shetland Sheepdogs among the dogs carrying two copies of a previously reported recessive black version. Merle has a special link to the breed: a 2006 study first linked the pattern to the PMEL gene in Shetland Sheepdogs before finding the same insertion in merle dogs of several breeds.
One merle copy gives the marbled pattern; two copies, from two merle parents, give a "double merle", and research has found double merles are much more likely to be deaf. Our guide to merle dogs explains the risks, and our coat colour hub covers how these genes interact.
Size
The CKC says a Sheltie should stand 33 to 41 cm tall at the shoulder, and the American Kennel Club gives a weight of about 15 to 25 lb, or 7 to 11 kg. Size varies within the breed, and small dogs tend to keep growing for less time than large ones; our guide to when dogs stop growing covers the timelines.
How long do Shelties live?
In a UK Kennel Club survey of owners, the median age at death of 56 Shetland Sheepdogs was 135.5 months, about 11.3 years, above the survey's overall median of about 10.3 years. Of the 25 common causes the study broke down by breed, Sheltie owners most often reported old age, unspecified cancer and cardiomyopathy, at 12.5% each, followed by kidney failure at 10.7%. The sample was small, so treat the figures as a rough guide. The American Kennel Club lists a life expectancy of 12 to 14 years.
The MDR1 drug-sensitivity variant
A variant of the MDR1 gene can make dogs dangerously sensitive to some common drugs. A 2004 study traced it to breeds from the working collie lineage. Of 190 Shetland Sheepdogs tested, 14.7% carried one copy and 1.1% carried two, so about one in six carried it.
If you have a Sheltie or a Sheltie mix, ask your vet about MDR1 before it's treated with drugs known to be affected. The PuppyGenes report doesn't include genetic disease or health screening, so it isn't a substitute for an MDR1 test.
Temperament and energy
The CKC describes the Sheltie as intensely loyal, affectionate and responsive, with a strong desire to please that has made it one of the foremost breeds in obedience. It's alert, agile and busy, and its exercise needs are easily met with a daily walk. Breed is a loose guide to any one dog, though: a 2022 study of more than 18,000 dogs found breed explains only about 9% of behavioural differences between individual dogs.
Sheltie mixes and DNA tests
The PuppyGenes breed ancestry section estimates a dog's breed mix as percentages, and the coat colour section reports merle where the sample supports interpretation, though in some samples merle can't be determined; if merle matters for breeding, ask about the parents. If you're weighing a test, our guides to whether dog DNA tests are legit and where to buy a dog DNA test in Canada cover what to check before you buy.
Frequently asked questions
- How big do Shetland Sheepdogs get?
- The CKC says Shelties should stand 33 to 41 cm at the shoulder, and the American Kennel Club gives a weight of about 7 to 11 kg.
- How long do Shelties live?
- In a UK Kennel Club survey, Shelties lived a median of about 11.3 years, though the sample was small. The American Kennel Club lists a life expectancy of 12 to 14 years.
- Is a Sheltie a miniature Collie?
- No. Shelties have small Collies in their history, but they're a separate breed from the Shetland Islands. They were first shown as "Shetland Collies" in 1906 and renamed after Collie breeders objected.
- What colours do Shelties come in?
- The CKC lists black, blue merle and sable, marked with white and/or tan. Breeders call the main combinations sable, tricolour, bi-black, blue merle and bi-blue.
- What is MDR1 in Shelties?
- A gene variant that can make dogs dangerously sensitive to some common drugs. In one study, about one in six Shetland Sheepdogs carried it, so ask your vet about testing.
From general to personal
See how this applies to your dog specifically.
Our at-home Complete Dog DNA Test adds your dog's own results to these tips across six report sections: breed ancestry, coat colour, physical appearance, temperament and size predictions, genetic diversity and oral microbiome. The report does not include genetic disease or health screening.