As a rule, you can tell a dog’s actual color by his or her nose. Genetically speaking, black dogs have black noses, and red dogs have liver colored noses as the liver gene is recessive, and it must have the genotype bb in order to be superficially present. Conversely, it’s genetically impossible for a liver dog to have a black or blue nose. Liver colored and “isabella” colored dogs have noses that can be anywhere from pink to deep chocolate brown. Liver pigment doesn’t appear to be retained in the nose as readily as black pigment which is why you see many high-white liver dogs with completely pink noses. The default nose color for a dog is black, and if you spot a black nose is at the business end of a reddish dog, the dog probably isn’t really red, but sable or yellow instead.
Speaking of impossibilities, it’s also genetically impossible for a blue dog to have a brown nose. If an apparently “blue” dog has a black nose and dark eyes, it’s because it’s really a black dog with the greying gene and not a proper blue dilute. It’s easy to get fooled. Some blues are so dark that their hair and nose look nearly black, and then it’s tough to discern if the dog is black or blue.
If there is a concerted effort on the part of a breeder to get the maximum allowable white markings in a litter, the puppies may have more pink on their noses because dogs with little to no white markings rarely have unpigmented noses. This shouldn’t be confused with some puppies that have a few tiny pink spots on their noses, those typically fill in with pigment by the time they’ve reached their first birthday.
A very helpful reader pointed out that use of the word “red” to mean bb is breed specific. One may usually see American Border Collie, Aussie, and MAS people use “red” to mean bb, and in those breeds, the coat usually does have a reddish cast. Some breeds call bb “liver” (because it’s more of a liver color in the breed), others “chocolate”, or “brown”, and that’s not even getting into Chessie color terms. In some breeds, “red” means ee while in others, “red” can refer to sable, which is itself called fawn in lots of breeds. But fawn in Beardies is bb dd, not sable. IIRC, “red” in dachshunds might be ee OR sable.
Image: To our knowledge, no breed standard calls for a green nose, but with Kathryn Wronski‘s brush and palette of oils, we can imagine it. This piece is “Curious Blue” from her “Thirty paintings in Thirty Days” series. Support this artist’s work here.