Doggy door is the only way to go. I have them coming into my garage and one into the main house. I can lock dogs and cats in different places that way. Garage is airconditioned also. If your worried about critters coming in through the doggy dor, they have ones that unlock with a collar you have on your dog.
I live in the sticks and have no problems with little critters as I spray around the house a couple times a year.
Do boxers drool?