Merle is a color pattern rather than a coat color formed by a solid base color (usually red/brown or black) with lighter blue/gray or reddish patches, which gives an uneven, marbled effect.
The merle pattern may be a typical breed characteristic such as in the Catahoula leopard dog (hence its name) and the Australian shepherd dog or a coat variety, which may or may not be recognized.
Breeds
Merle appears in the Australian Shepherd dog, Shetland sheepdog and Beaceron merle, but also in various Collies, the Koolie, the Welsh Corgi (Cardigan), the Pyrenean Shepherd, the Bergamasco Sheepdog, and the Old English Sheepdog. In Dachshunds the merle marking is known as "dapple". It is also present in the Pomeranian. The merle gene also plays a part in producing harlequin Great Danes. Hence, why merle Beaucerons are sometimes also referred to as Harlequin Beaucerons.
Blue merle as a recognized color variety
Australian Shepherd Dog
Basque Shepherd
Border Collie
Deerhound
Rough Collie
Shetland Sheepdog
Smooth Collie
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