Merle is a coat pattern commonly found in certain dog breeds, characterized by a mottled or marbled appearance. This pattern typically features patches of color mixed with lighter shades, creating a unique and striking look. Breeds like Australian Shepherds, Collies, and Dachshunds often exhibit the merle pattern. The merle gene can affect not only the coat color but also the dog's eyes, which may appear blue or have a speckled effect. While merle is visually appealing, it is important to note that breeding two merle-patterned dogs together can lead to health issues in the offspring, such as deafness or vision problems.