Harlequin dogs refer to any breed of dog that has a coat coloration pattern consisting of large irregular patches called merle. The term “harlequin” is used to describe this patchy color pattern in a variety of dog breeds.
What Does Harlequin Mean?
The word “harlequin” originated in the 15th century to describe a comic servant character in Italian plays that wore a costume with multicolored diamond patches. This patchwork appearance came to be known as “harlequin” and was later applied to dogs with a similar merle coat pattern.
Genetics of Merle Coats
The merle coat pattern is produced by a dominant gene that alters the development of melanin pigment in the dog’s coat. This causes a mottled or patchy distribution of color instead of a solid or homogeneous color.
The merle gene (M) is located on chromosome 10 and causes a dilution of eumelanin (black pigment). When a dog inherits the dominant merle gene (M) from one parent, it becomes heterozygous (Mm) and will display the merle coat coloration.
When a dog inherits two copies of the merle gene (one from each parent), it becomes homozygous (MM) and can develop health issues due to having little eumelanin pigment. For this reason, breeding two merle-coated dogs together is generally avoided.
Common Harlequin Dog Breeds
While any dog breed can display a harlequin merle coat, it is more commonly seen in the following breeds:
| Great Dane | One of the most familiar harlequin breeds, Great Danes have a base coat color of white with large irregular black patches. |
| Australian Shepherd | Australian shepherds exhibit great variation in merle coats, from mostly solid to heavily patched merle. |
| Catahoula Leopard Dog | This working dog breed native to Louisiana is known for its distinctive patched “leopard” merle coat. |
| Cardigan Welsh Corgi | The Cardigan Welsh corgi’s blue merle coat features black, gray, and white marbling. |
| Shetland Sheepdog | Shelties can have merle coats in various colors including blue, red, and sable merle. |
| Border Collie | Border collies are commonly seen with black-and-white or red-and-white merle coats. |
| Chihuahua | Merle Chihuahuas have become increasingly popular, exhibiting splashes of blue or gray. |
Great Dane
One of the most iconic harlequin dog breeds is the Great Dane. The harlequin Great Dane has a white base coat with irregular black torn patches distributed over the body. The head is typically mostly black with white markings.
To achieve the harlequin pattern, the Great Dane must inherit the merle gene from one parent. Breeding two merle Danes often results in excessive white markings and deafness. Responsible Great Dane breeders avoid doubling up on merle.
The harlequin Great Dane originated in the 19th century. The original German breed standard recognized four Great Dane coat patterns: brindle, fawn, blue, and harlequin. The harlequin was considered a fault until the late 1800s when the pattern became standardized and popular.
While striking in appearance, the harlequin Great Dane is prone to some health issues associated with the merle gene, such as deafness and increased risk of sunburn. However, reputable breeders test breeding stock for merle-related conditions.
Australian Shepherd
The Australian shepherd is another breed well-known for its merle patterning and harlequin-like coats. This energetic herding breed comes in a variety of base colors including black, red, and blue.
The red and blue merles have mottled patches of darker pigment over a lighter background. With the black-based merle, the dark patches appear on a white background, creating a harlequin look.
Since the merle gene can cause vision and hearing problems when doubled up, responsible Aussie breeders follow breeding protocols to avoid excessive white. Aussies should not have more than 30% white in their coat.
The Australian shepherd originated in the western United States as an all-purpose farm dog. Its exact origins are debated, but it likely descended from collies and shepherding dogs brought to North America by Basque immigrants.
The merle coat pattern was likely introduced into the breed from crosses with English shepherds. The Australian shepherd became increasingly popular after WWII and the harlequin merle coat emerged as a distinctive trait of the breed.
Catahoula Leopard Dog
The Catahoula leopard dog is a multi-purpose working dog bred in the Catahoula Lake region of Louisiana. It’s named for its distinctive “leopard-like” patchwork coat, which comes in a harlequin or merle pattern.
Also called the Catahoula hog dog, this breed’s coats come in a range of base colors including blue merle, red merle, black, and yellow. The leopard-like appearance comes from the merle gene producing irregular patches over the base color.
In some cases, the merle patterning is expressed as black or gray spots over a white base, creating a harlequin look. The head typically has colorful mottling and dark markings around the eyes.
The Catahoula breed likely descended from Native American and European dogs bred by early settlers in Louisiana. The harlequin-like merle coat emerged as a distinctive trait as the breed was refined to work livestock.
Catahoulas excel at herding feral hogs and cattle. Their merle coats served as effective camouflage when working in the dense forests of their native region. The patches also made the dogs identifiable from a distance.
Cardigan Welsh Corgi
The Cardigan Welsh corgi is one of two corgi breeds that originated in Wales as herding dogs. The breed’s colors include sable, brindle, black, and blue merle. The cardigan’s merle coat resembles a harlequin pattern.
The blue merle Cardigan Welsh corgi has a grayish or bluish marbled coat with deep gray or black patches. It may have tan markings around the eyes, legs, chest, and muzzle.
The merle mutation likely entered the Cardigan breed through crossbreeding with French herding dogs in the late 19th century. The marbled merle coat pattern was established as a defining feature of the Cardigan Welsh corgi by the early 20th century.
Reputable Cardigan breeders avoid breeding two merles together to prevent deafness and vision defects. The breed standard penalizes excessive white markings covering more than 30% of the body.
The patchy harlequin merle coat provided camouflage for the Cardigan Welsh corgi when herding livestock in its native countryside environment. The mottled coloring is now considered a hallmark of the breed.
Shetland Sheepdog
The Shetland sheepdog, affectionately called a “Sheltie,” is a small herding dog originally from the Shetland Islands north of Scotland. The breed comes in four recognized colors: blue merle, black, sable, and sable merle.
The blue merle Sheltie has gray and black marbling over a white background, resembling a harlequin pattern. Lighter copper or tan merling may also be present around the eyes, ears, legs, and underside.
The sable merle Sheltie has a mix of darker and lighter hairs over the body, producing a salt-and-pepper effect rather than distinct patches. Breeding two merle Shelties often results in excessive white markings.
Shetland sheepdogs likely descended from small collie-type herding dogs brought to the Shetland Islands by Viking settlers. The merle coat pattern emerged through crosses with spotted Border collies and other herding breeds.
The patchwork merle coat provided camouflage and made the Shelties identifiable from a distance while herding sheep in the rugged island terrain. Today the merle coat remains a signature feature of the breed.
Border Collie
The Border collie originated in the border region between England and Scotland as an indispensable sheepherding dog. Border collies typically have black and white coats, but also come in chocolate, yellow, red, sable, blue merle, and red merle.
The black-and-white border collie owes its coloration to the extreme white spotting gene rather than the merle gene. However, the merle variants produce a harlequin-like coat pattern with mottled patches.
The blue merle border collie has black torn patches over a marbled gray background, while the red merle has reddish-brown mottling. Excessive white caused by the merle gene can result in deafness.
Border collies likely inherited the merle mutation through crosses developed for herding dogs in the British Isles. The patchy merle coat provided camouflage when herding sheep in the hilly border country terrain.
While not typical of the traditional working border collie, the merle coat pattern became popular for the breed in the late 20th century with the rise of dog shows and companion border collies.
Chihuahua
The tiny Chihuahua may seem an unlikely candidate for a harlequin coat, but merle has become a trendy pattern in this breed. The merle Chihuahua has a marbled coat featuring darker gray or blue patches over a lighter background.
Merle Chihuahuas range from being mostly white to having large gray or blue patches distributed across the body and head. Breeding two merle Chihuahuas is strongly discouraged due to the risk of deafness and vision issues.
The origins of the merle coat in Chihuahuas are unclear but it likely appeared through outcrossing with other merle breeds. The patchwork coloring caught on as a novel pattern for conformation and companion Chihuahuas.
However, most major kennel clubs do not recognize merle as an official Chihuahua color. Controversy exists around merle Chihuahuas due to links between the merle gene and health problems. Responsible breeders avoid merle-to-merle matings.
While the harlequin merle Chihuahua has popular appeal, prospective owners should be aware of potential health risks associated with the merle gene being introduced into toy breeds not adapted to it.
Other Potential Harlequin Breeds
In addition to the breeds detailed above, other dogs that may occasionally display harlequin merle coats include:
– Pomeranian
– Shetland Sheepdog
– Bernese Mountain Dog
– Beauceron
– Koolie
– Corgi
– Miniature Pinscher
– Chinese Crested Dog
Since the merle mutation can occur spontaneously, it has the potential to turn up in any breed. However, it is not standard in most breeds and reputable breeders avoid merle-to-merle pairings to reduce associated health risks.
Health Considerations of Harlequin Dogs
While a harlequin coat is desirable in some breeds, the merle gene that causes it can increase the risk of certain health problems, especially when doubled up. Potential issues associated with harlequin dogs include:
– Deafness – Lack of pigment in the inner ear can cause full or partial deafness.
– Blindness – The merle gene can affect retinal development leading to visual impairment.
– Sun sensitivity – Lack of pigment in white fur can lead to sunburn and skin cancers.
– Eye defects – Merle dogs may be prone to development issues causing microophthalmia, abnormal pupils, cataracts.
To reduce the chances of these conditions, responsible breeders of harlequin dogs do not mate two merles together. They screen breeding stock for hearing, vision, and eye issues that could be passed on.
While some risks come with harlequin coats, these can be mitigated through careful genetic testing. Overall, harlequin dogs can make wonderful companions when bred properly. The vibrant patchwork coat remains a favorite among many dog enthusiasts.
Conclusion
Harlequin dogs exhibit a distinctive merle coat pattern of irregular color patches. The harlequin phenotype appears in many breeds but is best known in Great Danes, Australian Shepherds, and Catahoula Leopard Dogs.
The merle coat provides camouflage and visual distinction for working breeds developed in Europe and America. Breeders must take care to avoid doubling up on the merle gene, which can lead to vision and hearing impairment. When responsibly bred, however, harlequin dogs can make excellent working and companion animals.
