Yes. A shih zhu is a dog that you could argue is barely a dog. But...a dog still. Embarassing, but your Golden Retriever still have to claim it as kin. When that fluffy thing springs into a new species, let me know. Everyone is waiting to watch.
My labrador will never be anything other than a spoiled fat pooch who sleeps on the couch when I'm not home. However, consider for the sake of argument her children's children thousands of generations distant, bred by us for intelligence, loyalty, and other desirable physical traits. That superior descendant of the current dog may be sigificantly distinct from the dogs that exist today as to be considered a different species. It might not even be able to breed with contemporary dogs, if any were to still exist that far in the future. Or if so, the children of such a union might be mules, unable themselves to procreate.