merle

Merle is a genetic pattern in a dog's coat and alleles of the PMEL gene. It results in different colors and patterns and can affect any coats. The allele creates mottled patches of color in a solid or piebald coat, blue or odd-colored eyes, and can affect skin pigment as well. Two types of colored patches generally appear in a merle coat: brown/liver (red merle) and black (blue merle). Associated breeds include Carea Leonés, Australian Shepherds and Catahoula Leopard Dogs. Health issues are more typical and more severe when two merle-patterned dogs are bred together. Description Merle can affect all coat colors. The merle forms of brown are usually called "red" (though this is not correct; red and brown are genetically different), and black is called "blue" as lighter patches of black are formed throughout the coat and look slightly blue in color. Dogs who are recessive red can still be affected by merle, but the patches are either hardly seen or, if the dog is a clear recessive red, are not visible at all. Combinations such as brindle and sable merle exist, but are not typically accepted in breed standards. In addition to altering the base coat color, merle also modifies eye color and coloring on the nose and paw pads. The merle allele modifies the dark pigment, resulting in eyes or parts of eyes turning blue. Since merle causes random modifications, dark-eyed, blue-eyed and odd-colored eyes are possible. Pigmentation on paw pads and nose may be mottled by pink. Breeds Merle is a distinguishing marking of several breeds, particularly the Australian Shepherd and Catahoula Leopard Dog, and appears in others, including the Miniature American Shepherd, the Koolie in Australia, the Shetland Sheepdog, various collie breeds, the Cardigan Welsh Corgi, the Pyrenean Shepherd and the Bergamasco Shepherd. In Dachshunds, the merle pattern is known as "dapple". In Beaucerons the merle pattern is known as "harlequin". The merle allele also plays a part in producing harlequin Great Danes. Depending on the breed, registry or country, the pattern may be register-able with a registry but not allowed in conformation, and the pattern may not be recognized by the breed standard, disqualifying it from showing. There may also be additional requirements for the pattern such as the dog being allowed to have the pattern but must have completely dark eyes with no blue in them.