I dont think so no, they're a companion, like part of the family. Hence why I don't agree with breeding dogs for profit.
Just look at the dog thread for other examples of the issues with breeding animals for us.
That being said its a bit of a grey area for me personally because at least dogs are not being bred to be exploited or stabbed for food (apart from dog fighting etc.)
Well they are contributing. Dogs are predators and need to be fed meat as do many other pets.