Humans are rarely uniform in our approach to life, and I think that would include our treatment of dogs who are much more intelligent than humans. And instead of typing "dogs who are much more intelligent than humans" over and over again, I'm going to call them "peabodies."
It seems likely (because you don't say otherwise) that the peabodies have been around a long time -- more recently than humans, I'll assume, because dogs in general are a more recent development. But I think we would've encountered them before, say, the bronze age, though not necessarily on all continents.
Those who cooperated with the peabodies would likely prosper a lot better than those who didn't. Considering that for a lot of our existence, getting our next meal was often a problem, I think there'd be a lot of advantage toward cooperation. Those who used the peabodies' brainpower would tend to reproduce better and defend themselves better than those who didn't. And the peabodies wouldn't make very good slaves -- those unhappy with their lot would only have to hold back in inventing, and, of course, they'd know it.
Of course there would be exceptions, because humans of any stripe can be irrational. When Benjamin Franklin invented the lightning rods, churches considered them blasphemous. But when church towers kept getting hit by lightning and structures protected by lightning rods were kept safe, the lightning rods won. We're a species with a certain frequent self-defeating perversity to our thoughts, yes, but we're not, generally, idiots.