Dog breeds are not real animals, they're some sort of half-artificial thing created by imperfectly writing some people's desire into another species's genetic code.

If you make an artificial thing that really wants to do some specific thing, like a computer endlessly printing "hello world" millions of times a second, it's not surprising to see it do the thing it was created to do. I wouldn't say the computer "wants" to print hello world, so I don't see the dog as doing what it truly wants to do if it's a genetic predisposition human breeders forced into it. I see the expression of a society of dog breeders and people's idea of a game called "fetch" which was relatively easy to transition a species towards step-by-step using artificial selection.