Dogs and wolves are cross fertile (which has caused problems for the preservation of an endangered species of wolf in the Ethiopian highlands (13,000 feet) because loose dogs keep mating with the wolves). If there is an essential difference between dogs and wolves it is in the attribute of tameness. No dog who was not more tame than a wolf would be a dog. So the essential characteristic that dachshunds and Dobermans share is docibility. The color of a dog's fur, on the other hand, is an accidental trait, and even if an owner breeds dogs for a certain color, coat color is not an essential property of any dog--a change in coat color would not affect his "dogness."
Please address the problem of axioms or self-evident propositions, Simplicimus. When you claim that it is arbitrary to privilege essential traits, it is as if you were claiming that there is no such thing as relevance. You must respond to my suggestions for beginning points if the dialogue is to go forward.