The EM-locus is a variant of the E-locus that causes a dark mask. This mask is visible on light...plus
Analysis reveals whether a dog with a mask has one or two copies of this version of the extension locus. Animals with a single copy can produce offspring with or without a mask, while those with two copies will only produce masked offspring. The test may also be applied to black dogs where it may not be possible to tell if there is a mask.
3-5 days after arrival of the sample in the lab