I think the answer lies in the concept of 'gentility'. When hall in the lord's house was a mixture of local courthouse, family den, servants' mess room, village meeting place and party room, the dogs would have been simply part of the scene and would have been useful for keeping the floors food-free and catching rats.
The solar or private room would presumably have been accessed only by favourite dogs. In Tudor and 16th century houses,although notions of grandeur have crept in eg plastered ceilings, fancy grand staircases, you still see in some parts a gate across the bottom of the stairs to keep the dogs out of the best rooms. In the same houses, it's often the case that the ground floors were flagged with stone and strewn with sand to absorb who knows what, with only the upstairs having nice timber floors.
Round about the same time, you get the notion of a 'withdrawing room' ie what later became a drawing room, so the owner could parade his finesse and learning to any visitors who might understand or be impressed by it.
Things got seriously snobbish in the 18th century, when 'gentlemen' were recognised as such because their servants, dogs and means of living were kept at a distance from their increasingly refined lives, and those of their delicate womenfolk.