I am looking for some packs that would fit the dogs, although they are small (Boston Terrier mixed breeds), they can carry some of their own gear.
Kelty makes a dog pack that fits my JRT who's about 22 lbs and 8-10" high at the shoulder. One thing I've read is that dogs shouldn't carry more than 10% of their body weight. My dog's pack carries a couple days of food, waste bags and a spare leash. I carry an extra water bottle with a built in trough for the dog.
By the way, a little dog with a backpack really makes women go "Oh, isn't he cute?", the dog, not me...