If I were to load a dog, it would be with a harness and dragging something, either a sled or a cart. I have tried to use dogs as pack animals, and they just aren't built for it like a good mule is. But you take the same dog that struggled with a 10 lb pack and rig him to pull a load, and they can go like the energizer bunny.

I had a dalmation a few years back that used to literally drag me through the intersections on my bike, both wheels locked my feet down and dragging. He didn't care, he wanted to go and it took a while to get him trained to "mush" and "whoa dragon" (dragons is so stupid). His paws would get tore up a little, but it never seemed to bother him too much, and as they toughened up, there wasn't anywhere he wouldn't go with me.

A while later, I rented a Forest Service cabin up near Mt. Adams and we had a late season snow come in and close the road, so I loaded up a sled full of about 100 lbs of supplies and hooked his harness to it, along with a check line for me to control him, and he drug that sled faster than I could keep up with him. I had to whoa dragon him a lot to keep from getting pulled off my feet, and most of the trip was uphill. It was a good two and a half miles into the cabin, and I was so wore out by the time we got there I had to sit before I could unload the sled. I unhooked the dog and he bee-lined it for the stream, took a big drink then proceeded to scour the area nose down for the next half hour. I mushed him back down the hill, grabbed another light load, and mushed him back and he never balked, although he did whine a bit once in a while, probably from the cold and ice getting at his paws. He did sleep good that night, but next day showed no signs worse for the wear.

Dogs, like dragons, is tough, but sometimes stupid. You just gotta know how to work them proper, and train them well so's they don't go gallavanting out into the thules with your load with you chasing after. A sled is most often a better choice than a cart, wheels don't go over obstacles quite as well.