Canine Coat and Nose Color Testing

Presence of tricolor and sable colors. There are two "a" alleles at the agouti locus in Collies which cause the three main coat colors. Each of these may occur with or without merle. At the present time there is no DNA test for merle, but since the merle pattern is exhibited by the Mm heterozygotes, the phenotype is predictive of the genotype. Note that MM dogs are primarily white and conscientious breeders avoid producing such dogs since deafness is typical and eye defects are also common. DNA testing for the "a" alleles in Collies that are sable or tricolor allows breeders to better predict the colors of pups from particular matings. Although some breeders believe they can "see" the difference between a homozygous and heterozygous sable, this has not been reliable. Some breeders refer to dogs that are homozygous sable as "clear for sable". Collies are all EE and BB so although tests for the other alleles at these loci are available in our laboratory, these tests are not needed in Collies.