Aussie Genetics Fact Sheet
by C.A. Sharp
Phantom merles, more properly called cryptic merles, are dogs which carry a merle gene but are phenotypically (look like) tri or bi. Most such dogs will have some small area of merling somewhere. Theoretically it is possible that a dog would have no merling and be a cryptic merle, but this would be extremely unusual. Sometimes the only merle spot will be on the tail which is docked in Australian Shepherds.
Cryptic merles should be registered as merles because they will breed like merles. If bred to a non-merle, merle puppies will be produced. If bred to another merle, homozygous merle puppies will probably be produced. Merle offspring of a cryptic merle will virtually always be "regular" merles, not cryptic merles.
Excessive white markings in puppies from a tri-to-merle cross are not "proof" that the tri (or bi or solid color) parent is a "phantom merle." Excessive white markings in such a cross are the result of genes which code for white trim and have nothing to do with merle.