The "Merle" Gene

Merle is not the name of the dog or the name of the color of the dog. The term merle is used to describe the unique spotting marking of the animal's coat. The merle gene is a diluting gene that affects the dark coat colors normally seem in dogs. This strong dominant gene combines with the solid colors to create the merle pattern: multi-color patches all over the dogs’ body. For a dog to be a merle, it must have one merle parent. Dogs with the merle gene may have blue eyes, one blue eye and one brown eye, or one or both eyes might be bluish-brown. Two merles must never be bred together as there is a 25% chance per puppy that it will result in a defective, homozygous double-merle. The resultant animal's coat will be diluted twice and it is typically white or may have very few light spots. These puppies can have birth defects such as blindness, deafness and/or defective or missing organs. Merles should only be bred with non-merle mates of a darker color. Merles should not be bred with light color dogs as all of the offspring will possess the merle gene and the merle markings might not be visible on a lighter colored dog. A responsible merle breeding program can be very exciting, producing beautiful results.