Glossary

Merle

A coat pattern with patches of diluted colour on a darker background, seen in breeds such as the Australian Shepherd, Collie and Great Dane.

Also called: merle coat, dapple, double merle, blue merle, red merle

Merle is a coat pattern caused by a single gene that dilutes colour in random patches. The result is a mottled coat, often with blue or odd-coloured eyes. The pattern appears in breeds such as the Australian Shepherd, the Collie, the Shetland Sheepdog, the Cardigan Welsh Corgi and the Great Dane. In Dachshunds, the pattern is called dapple.

A dog with one copy of the merle gene is a merle. A dog with two copies, called a double merle, comes from mating two merles and can be mostly white, with a greater chance of deafness and eye problems. For this reason responsible breeders do not pair two merles. A Dog DNA test can identify merle, including hidden merle in dogs that look solid.

The pattern is a colour trait only, not a sign of rarity or quality. Ask a vet about hearing and vision concerns in any dog with merle ancestry.

Last reviewed November 8, 2026

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Related terms

Brindle A coat pattern of dark, tiger-like stripes over a lighter base of tan, fawn or red, seen in Boxers, Greyhounds, Bulldogs and many others. Sable A coat colour in which each hair is banded or tipped with black over a lighter base, giving a shaded look as in many Collies and German Shepherds. Genetic diversity The variety of genes within a breed or population; closed stud books and heavy use of a few popular sires reduce it and make inherited conditions more common. Health testing The screening of breeding dogs for inherited conditions, such as hip, elbow, heart, eye and DNA tests, whose results are shared with buyers.