Basic description for the beginner: What looks-like
for intents and purposes an animal who is a non-merle. Which in no
way bares any physical characteristics of being merle but genetically is in
fact merle (Mm). This is known as a "hidden," phantom or cryptic merle. When
these hidden merles are bred they produce merle offspring.
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.
Testing can now be done to determine if your pet is merle. Refer all questions on testing your pet to: