Sure,
I like to do a lot of hiking on foot and don't enjoy carrying more than I have to. I have my pack down to about 15 lbs before food and water, and because my dog (Plato) is fairly big he requires a lot of food and water, especially in the outdoors in the heat (and I live in Texas). It would break my heart to leave him at home, so the only solution is to sack him up and make him carry his weight. He can carry about a weeks worth of his own food and 3 days of his own water. Plus it works out well because he tends to stay close and have less tendency to wander when he's loaded down. Without the pack he may run off on his own more than I like.
I picked it up at REI, although I'm sure you can get it other places cheaper. They let me take my Plato in and test fit em which I thought was nice and their return policy can't be beat.
REI has a great selection of dog outdoors gear.
I tried several different brands and sizes on him and the one you see in the picture is the one that fit him the best. Fit is particularly important or the dog will usually try to lose the bag, or worse it can injure them.
Their dog pack section is
HERE.
The pack I ended up going with is HERE.
[URL="http://www.rei.com/online/store/ProductDisplay?productId=47641338&storeId=8000&catalogId=40000008000&langId=-1&color=RED/WROUGHT%20IRON&img=/media/767212.jpg&view=large
Good luck!