Is merle in dogs a defect?
An autosomal, incompletely dominant trait, merle coat coloring predisposes dogs to inherited deafness. When inherited in the homozygous state, the merle mutation causes dogs to be white and have an even greater incidence of deafness, blindness and sterility.
Is merle a birth defect?
Merle is actually a heterozygote of an incompletely dominant gene. If two such dogs are mated, on the average one quarter of the puppies will be “double merles”, which is the common term for dogs homozygous for merle, and a high percentage of these double merle puppies could have eye defects and/or be deaf.
What kind of dog is a merle?
Merles aren’t different from standard dogs, only that they are more beautiful and, sadly, prone to health issues such as deafness and blindness. The most defining characteristic of a merle dog is a mottled coat of black, tan, or white colors. Odd or blue-colored eyes also define these breeds.