Dogs can't carry a whole lot of weight. But, as sledders know, they can be used to pull several times their own weight if a suitable vehicle is provided. A simple cart or travois can be used. A travois has the advantage that they can be made quite stable by making them wide with the weight riding low, are inherently rugged, and they are far less prone to running away and hurting the dog. Simple bands across the shoulders and another in front, three sticks and some lashing is all you need.

American indians sometimes used dogs this way. I've been told that when harnessed the dogs are far less prone to running off and getting into trouble.