If you apply this question to workers in shelters, then the answer is fairly obvious — it helps a dog’s odds of being adopted. “Collie/Shepherd” sounds much more appealing than “80 pounds, sable and black.” A friend in the South notes that large black dogs aren’t adopted unless they’re called a Lab mix.
Of course the validity of such labels varies with the expertise of the people applying them. It helps to be familiar with a wide variety of breeds. That way, there’s less tendency to jump to the most obvious choice — a medium-size black and white dog being a Border Collie, for example. It could be a black and white Lhasa Apso mixed with something bigger, or even a Boston Terrier mixed with something bigger and hairier. Perhaps an even better indication would be does the dog act like a herding breed? After size, personality (or temperament) matters most to the majority of adopters. Shelters or rescues where workers actually get to know the dogs can provide this information more reliably and factor it into possible breed identification.
An understanding of the basics of trait inheritance also helps avoid automatic misidentification. For example, brown coat is recessive. So two black dogs can each carry the recessive gene for brown, and produce brown offspring. Without understanding this, you can be boxed into seemingly obvious, but actually inappropriate, choices.
The more difficult question is why people casually encountered by the mixed breed owner with her or his dog(s) seem to feel some obligation to identify the dog. These are not the mixed breed owners themselves, who delight in playing the “what made that dog” game. These are simple on-the-street momentary encounters.
An acquaintance owns a deerhound, a wolfhound, and a shelter rescue that is probably large part Border Collie. Not only are her purebreds misidentified as mixes (the deerhound as Greyhound-Labrador), the rescue receives oddly contrary results. If she ID’s the rescue as a mix, the stranger hastens to say he’s obviously a purebred. You might think they are just being polite, thinking that a purebred somehow has more value than a mixed breed. But if the owner simply says the dog is a Border Collie, the stranger is just as quick to say that he’s a Border Collie mix. It’s hard to know the impetus behind this contradiction, but it may stem from an innate human desire to appear knowledgable.
Next time: The story of a mixed breed who went from torture to competition