I keep my bikes in the garage and I live in NE Indiana where it gets really cold in the winter and fairly high humidity in the summer. My bikes are hanging from the ceiling and the most valuable ones are secured with a thick cable lock.
The dog thing? While I do have a dog but she stays in the house and not the garage, besides all someone has to do is feed the dog a meatball with a sleeping agent and wait for the dog to go to sleep. If someone wants something bad enough they're going to get it. Even alarm systems that may activate, assuming the theft is ignorant about how to neutralize one, they aren't ignorant to the fact that it will take the cops at least 3 minutes to get to the house and by the time the burglar is gone, and if the burglar is stealing a bike they could just ride it down the street with cops passing by and they would never suspect the bike rider as the thief.