What is a MERLE coat?
A merle dog has a base coat of a solid colour with patches and mottled areas of other colours.
A brindle has a pattern of dark and light striping in the fur. There are black, chocolate, red & silver brindles.
A mosaic coat has patches of colours. It is not a colour variety carried by genes. It is rare and likely caused by a colour gene mutation.
K locus alleles determine the colouring pattern of a dog's coat. M locus alleles determine whether a dog expresses a merle pattern to its coat.
A brindle pattern will be expressed if the dog has one kbr allele and no KB allele.