If the dog is medium-sized, or willing to sleep in the vestibule, then your options change. The North Face's Peregrine ($319) has vestibules on both sidesone for your gear, one for the dog. Or, take a look at Mountain Hardwear's Mountain Wing 2 ($275), which borrows TNF's wings-out design for a vestibule on each side.
Pack a sleeping pad for the dog, tooa light Ensolite pad or similar is fine. And if your hound is accustomed to sleeping in a warm, snug house, consider their warmth when camping as well as yours. The pad will help, but you might also take a small Polartec blanket. That will weigh only a pound or so but may obviate having to share a sleeping bag with Astra, or Buddy, or whatever his/her name is.