The breed standards state “All colors are strong, clear and rich. The recognized colors are blue merle, red (liver) merle, solid black, and solid red (liver) all with or without white markings and/or tan (copper) points with no order of preference. The blue merle and black have black pigmentation on nose, lips, and eye-rims. Reds and red merles have liver pigmentation on nose, lips, and eye rims. Butterfly nose should not be faulted under one year of age. On all colors, the areas surrounding the ears and eyes are dominated by color other than white. The hairline of a white collar does not exceed the point at the withers. These are all distinct genetic traits and breeders need to understand how they are inherited.
Black is dominant to liver, therefore a liver colored dog (whether merle or not) can only pass along genes for liver and when bred to another liver-colored dog all resulting puppies will be liver. A black dog, on the other hand, may produce puppies of either color if it happens to carry a liver version of the gene, referred to as ‘red factored”. Those with no liver version will never produce liver colored offspring. You can determine whether a black dog is red factored several ways: If it has a liver parent or offspring, by doing a DNA test, or by breeding it to a liver colored dog to see if you get liver puppies. If you try the test mating you need six puppies to be 98% sure of the result – all black would mean the dog is not red factored but even one liver pup would mean it is.