The Six Sheltie Colors

There are six distinct Sheltie colors: Pure Sable, Mahogany Sable, Tri Color, Blue Merle, Bi Black, and Bi Blue.

The Sheltie coat colors are further defined by their distribution of colors, such as the Irish pattern or the Piebald pattern (also known as white factoring). Here's a rundown of the Sheltie colors and the Sheltie color genes that produce them.

At a glance: the Sheltie colors.

1. The Pure Sable Sheltie

The Sable coat creates that classic Shetland Sheepdog look; the one that summons joyous cries of "Aww look! A mini Lassie!" The Pure Sable Sheltie is predominantly golden or tan with white patches on the chest, neck, and legs.

The Pure Sable Sheltie.

Pure Sable puppies are born with gray fur which slowly intensifies to tan as the coat matures. Here's our Sable Sheltie puppy, Howard, at around 8 weeks old and later at one year old.

Our Sable Sheltie, Howard, in his puppy and adult coat.

2. The Mahogany Sable Sheltie

The Mahogany Sable Sheltie develops darker fur in the realm of chestnut or mahogany, which is often tipped or heavily overlaid with black.

The Mahogany Sable Sheltie.

Also known as Shaded Sable, this Sheltie color develops over the lifetime of the dog. At one year old, Piper was deep tan with lots of black tips around his neck. Over the years, his colors grew darker until his main body was dominated by solid black fur.

Our Mahogany Sheltie, Piper, at 1 and 15 years, demonstrating the Shaded Sable coat development.

3. The Tri Color Sheltie

The Tri Color Sheltie is mostly black, with flashes of tan and white per the Irish pattern. In many dog breeds, Black is the dominant color variant; that's why so many dogs are black. But the dominant color variant in Shelties is Sable, making Black recessive. So a Tri Color is really an expression of a recessive Sheltie color gene. Shelties share this Sable dominance with Rough Collies, Corgis, and Pomeranians.

The Tri Color Sheltie.

4. The Blue Merle Sheltie

Look at this handsome devil. Is this Sheltie blue? Is he gray? Is he silver? Only he knows. The rest of us call him a Blue Merle, for his abundance of blue-gray fur, spiced up with a mottled pattern. This is known as dappling in other dog breeds, or merling in Shelties.

The Blue Merle Sheltie.

As we'll see in a moment, the genetics of Shelties color means the Blue Merle Sheltie is essentially a Tri Color with modifications. The Merle gene dilutes what would otherwise be black fur into various shades of gray and blue.

5. The Bi Black Sheltie

The highly unusual Bi Black Sheltie has solid black hairs which make up most of the coat color, complemented by the white Irish pattern. This distinctive two-color combo is so-named because bi is Latin for two.

The Bi Black Sheltie.

6. The Bi Blue Sheltie

Finally, perhaps the rarest Sheltie color of all, Bi Blue Shelties are distinctively gray or blue, with the usual white Irish distribution. Bi Blues also have varying degrees of merling. Genetically speaking, they're Bi Blacks with Merle modifications.

The Bi Blue Sheltie.

The Sheltie Color Genes

According to The Colors of the Sheltie: The New DNA Findings, there are at least 11 Sheltie color genes. The main ones control the base coat color, dilution, and pattern. There are also minor genes which control ticking, spotting, and progressive graying.

Here's a quick genetic glossary:

Let's consider two major color genes in Shelties:

The Agouti Gene controls the amount of tan or black in the coat, and influences whether those hairs are banded or solid in color. It comes in three alleles:

The Merle Gene controls whether dark fur and eyes are diluted (usually, from black to blue). The Merle gene is an interrupter of the Agouti gene. It comes in two alleles:

Predicting Genotypes

Punnett squares help predict the variations and probabilities of each genotype. Column one (mother) and row one (father) show the potential alleles in the eggs and sperm, respectively. Each puppy winds up with two copies of the gene in almost all body cells.

If both Mom and Dad carry both the M and m alleles, each puppy has a 75% chance of being Merle. (We'll look at the implications of Double Merle in a moment). The M allele is dominant, meaning it reduces or eliminates the effect of the recessive m allele when paired together.

Now the Agouti genotypes. While each parent carries up to two alleles of a single gene, there can be many different alleles across the overall Sheltie population. This table shows the possible genotypes of all the Agouti allele pairings. The dominance order is: a^y > a^t > a.

Bi Factored (BF) and Tri Factored (TF) are Mahogany Sables that carry the dominant Sable allele, plus a recessive Bi Color or Tri Color allele, which is expressed to a lesser degree.

Bi Color is a term that describes the Bi Black and Bi Blue phenotypes, the distinguishing factor bieng the presence of the Merle allele.

Predicting Phenotypes

Now smash those Agouti and Merle genes together and what have you got? A very cool range of variation in coat patterns. The genotypes of the six underlying Sheltie colors are:

Pure Sable	Mahogany Sable
Agouti: ayay	Agouti: ayat / aya
Merle: mm	Merle: mm

Tri Color	Blue Merle
Agouti: atat / aat	Agouti: atat / aat
Merle: mm	Merle: Mm

Bi Black	Bi Blue
Agouti: aa	Agouti: aa
Merle: mm	Merle: Mm

These are just the two main color genes in Shelties. Earlier I mentioned there are at least 11 color genes! Each puppy inherits a specific combination of alleles which combine to create variation in Sheltie colors and patterns.

Double Merles

The thing about genetic mutation is that sometimes it's good and sometimes it's bad. Positive mutations create variation and evolutionary adaptation. Negative mutations create disease.

As we saw in the Punnett square example earlier, breeding two Merle Shelties together creates a 25% chance of producing a Double Merle puppy. This has serious health consequences. Besides a striking all-white coat, the lack of melanin impacts the development of the eyes and ears in the womb, meaning many Double Merles are born blind and deaf.

What's more, while each individual offspring of two Merles has a 75% chance of inheriting a healthy Mm genotype, remember that Shelties have litters of 4-6 puppies. Statistically, one puppy in the litter has a 100% chance of being born a Double Merle.

Color Headed Whites

With all these genetic elements at play, there are plenty of combinations that can make unusual Sheltie colors, even if we don't see them that often.

For instance, the Color Headed White (or CHW) Sheltie has a virtually all-white coat, except for his head markings. CHWs look like regular Shelties who've been dipped in white paint from the neck down.

The Color Headed White Sheltie.

Color Headed White Shelties were excluded from the breed standard in 1952. Nowadays, when a Sheltie has more than 50 percent white markings, he's automatically disqualified from Conformation. As a result, breeders rarely try to produce CHWs today.

Color Headed Whites don't have the hearing or vision defects suffered by Double Merles because their coloration doesn't come from the Merle gene. Instead, they come from breeding two White Factored Shelties together.

White Factored Shelties

White factoring refers to the extent of white markings on the coat. If a dog is White Factored, it means they have an abundance of pure white fur, usually on their collar, chest, and legs, with a strong white stifle running up the back leg.

The White Factored Sheltie.

The color gene responsible for this is called the MITF gene. It directs all spotting and white markings on the coat. The dominant allel (s) creates a White Factored Sheltie, while the recessive allele (S) creates a Sheltie with the more common Irish pattern.

As you can see from the Punnett square below, crossing two White Factored Shelties with the Ss genotype can produce a range of patterns in the offspring. Each individual puppy in the litter has a 50% chance of being White Factored, a 25% chance of having the Irish pattern, and a 25% chance of being a Color Headed White.

White factored Shelties can be valuable to breeders in producing sufficient white markings in puppies. They're prized in dog conformation, as long as the white fur doesn't exceed 50 percent of the body, nor show up as conspicuous body spots.

White Factoring is seen in all the Sheltie colors: Pure Sable, Mahogany Sable, Tri Color, Blue Merle, Bi Black, and Bi Blue since it's a modifier of the Agouti gene. And just like Merle Shelties, White factored Shelties can also have those amazing blue eyes.

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To learn more about the wonderful world of Shetland Sheepdogs, download my 160-page PDF ebook, Shelties: The Complete Pet Owner's Guide, now in its fifth edition. The guide features hands-on advice on raising a Sheltie illustrated with 100+ photos from Sheltie owners around the world. It's much loved by those who followed the adventures of Howard and Piper Woofington Moon, the inspiration behind Sheltie Planet. Click here to learn more.

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