Why Can Merle Coats Lead to Problems in Dogs?

Posted by Christy Caplan
Blue Merle

Merle is a genetic pattern found in a dog's coat. Merle comes in different colors and patterns affecting all coat colors. The merle gene creates spotted patches of color, often blue or odd-colored eyes, and can affect skin pigment as well. These are beautiful patterns!

While the term 'merle' is often linked to blue merle, which is the most common coloration found, merle also creates chocolate or red coat patterns, too.

What is the merle coat pattern?

Merle is the name given to a certain specific coat pattern that can be found in dogs, rather than a particular color.

Pets4Homes tells us "the merle gene leads to a mottling pattern across the coat, which is reflected in the skin pigmentation."

"The gene that leads to the merle pattern does more than simply dictate the pattern of the coat itself - it can also lead to a range of potential congenital health issues in affected dogs, depending on the gene combination they inherit."

What breed is this commonly seen in?

Dogster says the merle (also called dapple) pattern is commonly seen in Catahoula Leopard Dogs, Australian Shepherds, Collies, Shetland Sheepdogs, Dachshunds, Cardigan Welsh Corgis, and Great Danes.

Though rare, Chihuahuas, Border Collies, Pyrenean Shepherds, Beaucerons, Pomeranians, and Cocker Spaniels breeds also have traces of merle in their lineages.

What color is a blue merle?

A blue merle is a black dog whose coloring has been genetically diluted. Parts of his black coat remain intact, while other parts take on a bluish-grey color. Patches of solid color are normally irregular in shape and are located anywhere on the dog's body.

What are the specific health concerns in merles? 

Dogster also shares that there are many health concerns pet owners should have on their radar:

"Dogs that inherit the merle gene have increased risk factors for congenital deafness in one or both ears, although this is not prevalent across single-merle dogs as a whole.

"Dogs with the double merle gene may also inherit a range of other traits that occur due to the genes that lead to the merle colouration. Congenital deafness is one of these, and ocular defects or problems with the eyes is another. Improperly developed eyes and blindness often accompany the blue-eyed trait in double merle dogs."

Merle comes in different colors and patterns and this can affect all coat colors. The blue merle Border Collie and blue merle Australian Shepherd are the dog breeds most people are familiar with when they think of 'merle' coat colors.

Merle coloring often comes with different eye colors too.  Merle puppies are adorable! Other dog breeds you may see in this color pattern? There are merle Pit Bulls, merle Shelties, merle Aussies, and merle Shetland Sheepdogs.

Do you know any merle breeds? Please leave us a comment below!

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Why Can Merle Coats Lead to Problems in Dogs?