8 Things to Know About Blue Merle Shelties

The Blue Merle Sheltie coat color is diluted to gray-blue with merle mottling

The Blue Merle Sheltie coat color is diluted to gray-blue with merle mottling.

#1. Blue Merle Shelties Have a Color Dilution Gene

Blue Merles have a special color modifier gene that you wont find in Sable or Tri-Color Shelties. This dilutes the base color of the Sheltie, changing it from predominantly black to light blue or gray, which is how Blue Merle dogs get their name.

The merle part of the name refers to the irregular patches of black, white, and tan that can appear speckled throughout the blue.

Thanks to this modification gene, Blue Merle Shelties have less melanin pigment in their fur. Less pigment means less color, resulting in... yes, blue Shelties!

The gorgeous face coloring of a Blue Merle Sheltie

Check out that merle Sheltie face.

#2. Blue Merle Shelties Can Have Different Color Eyes

Melanin also affects eye color, such that Blue Merle Shelties often have at least one blue eye, while the other eye is typically brown.

Blue Merles can also have two blue eyes, or even one-and-a-half blue eyes! In this case, one eye is part-blue and part-brown; it just depends on the color of the surrounding fur.

A Blue Merle Sheltie with two blue eyes

A Blue Merle Sheltie with two blue eyes.

#3. Bi-Blue Shelties Also Have The Merle Gene

The merle modifier gene affects a few Sheltie colors. For instance, it's seen in Blue Merle Shelties, Bi-Blue Shelties, and Sable Merle Shelties.

Without this genetic mutation, these would be your standard Tri-Color, Bi-Black, and Sable Shelties, respectively.

Hey, no-one said genetics was easy. But if you're into it, do take a deep dive into Sheltie genetics in the research paper, The Colors of the Sheltie: The New DNA Findings.

A Bi-Blue Sheltie is the result of a Bi-Black gene meeting a merle modifier

A Bi-Blue Sheltie is the result of a Bi-Black gene meeting a merle modifier.

#4. Breeding Two Merles Creates Double Merle Shelties

The thing about genetic mutation is that sometimes it's good, and sometimes it's bad.

This is common when two Blue Merles are bred together. The double exposure to the gene creates a 1 in 4 chance of creating a Double Merle Sheltie, also known as Double Dilute, or Lethal White.

Double Merle Shelties

Double Merle puppies have an all-white coat and frequently suffer from serious health consequences.

#5. Double Merle Shelties Are Often Blind and Deaf

Double Merle Shelties often suffer from incomplete development of the eyes and inner ear nerve endings while growing in the womb.

It's common for Double Merle puppies to be born with very small or non-functional eyes, causing blindness. Sometimes they can be born with no eyes at all.

They can also be born deaf and have a shorter lifespan than healthy Shetland Sheepdogs, which is normally in the range of 12-14 years.

While breeding two Blue Merles leads to healthy puppies 75% of the time, it's still pretty reckless to do so given that Shelties have litters of 4-6 puppies.

Each puppy has an equal 25% chance of inheriting the "MM" genotype and becoming a Double Merle so, statistically, at least one puppy per litter will be born with a serious congenital condition.

#6. Blue Merle Shelties Can Be Cryptic

It's not enough for breeders to examine a Sheltie's coat and conclude they don't have the merle gene. Sometimes it can be hiding.

Cryptic Shelties carry a merle gene that's barely expressed. While they may look Tri-Color, they're actually Blue Merles, with the hidden potential to produce Double Merle puppies.
Rebel is a cryptic Blue Merle Sheltie who appears Tri-Color

Rebel, a cryptic Blue Merle who appears Tri-Color, by Belmark Shelties.

Traditionally, breeders refer to pedigrees to trace the genetic lineage of each parent and identify such patterns of inheritance. Nowadays, they can perform a dog DNA test to be certain of whether or not a Sheltie possesses the merle gene.

Dog DNA tests aren't just useful for breeders. It's becoming more common for pet owners to screen their dogs for genetic diseases. If there are any red flags, you can can take early action like making lifestyle adjustments or giving preventative medication.

A dog DNA test involves taking a cheek swab from your Sheltie and mailing it to the lab. In return, you'll get a detailed report on her susceptibility to 210+ genetic health conditions and drug sensitivities.

Dog DNA Tests can identify 210+ genetic health issues in Shelties

Pick up a dog DNA test at Amazon from $139.

#7. Blue Merle Shelties Compete in Conformation

Blue Merles can compete and win Champion status at dog shows, alongside purebred Shelties of Sable, Tri-Color, Bi-Blue, and Bi-Black colors.

In Conformation, judges assess Shelties on how closely they meet the Shetland Sheepdog breed standard. While it may look like a beauty pageant, it's actually a way to determine their capacity to produce puppies with the optimal appearance, temperament, and gait.

If it seems awfully fussy and perfectionist—it is! Breed standards and Conformation help maintain the quality of the 190 official dog breeds in the world today.

In the video below you can see various Sheltie colors competing at the Westminster Kennel Dog Clue Show. Judges are looking for any deviation from the breed standard. For Blue Merle Shelties, they deduct points on the coat for rustiness, faded, or washed-out colors—as well as self-color which means a lack of mottling.


#8. Where to Blue Merle Sheltie Puppies

So you've fallen in love with Blue Merle Shelties and want to invite one to come and live with you?

Your first port of call is your nearest Sheltie rescue. While you're more likely to find the more common Sable Shelties, you won't know until you look. And need I say that adopting a Sheltie of any color is pretty awesome, so don't get too hung up on the Blue Merle coat.

If you're set on a Blue Merle puppy, contact a professional Sheltie breeder in your region.

Find Blue Merle Sheltie puppies from a reputable breeder

Be sure to find a Blue Merle Sheltie puppy from a reputable breeder.

Ethical breeders are not driven by the pet trade, by do occasionally have pet quality puppies for sale in their efforts to produce champions. Check their websites to see if they have Blue Merle Shelties in their current breeding stock, or reach out to say you're interested in going on their waiting list.

Just want to gaze at some puppies? Check out these 101 cute Sheltie puppies sent in from our readers.

Lastly, take a moment to see the happiest Blue Merle Sheltie in the world! I can virtually guarantee this will brighten your day...


Becky Casale

Becky Casale is the creator of Sheltie Planet and Science Me. Over the years she acquired a vault of knowledge about Shetland Sheepdogs through hands-on experience, breeders, trainers, pet owners, and the scientific literature. She lives in New Zealand with Pete, Fox, Kea, and Piper.


Shelties: The Complete Pet Owner's Guide