The odd thing about "dumb labor" is that many of those tasks are only easy for humans. Dealing in a messy world of human-to-human interfaces and cluttered unstructured worksites is generally hard for robots.
The dog for instance might be able to drag a load, but would probably need help refilling it.
I expect dog to have a robotic hand and eyes, so it could refill himself, move bricks to a target location and put them onto the top of the wall, use stairs and so on. Of course it should not be a one-trick pony, the whole point is in something universal which could easily configured to perform different tasks.
The dog for instance might be able to drag a load, but would probably need help refilling it.