While always open to alternative thinking, I believe the convention of using horses for logging rather than Welsh Terriers is fairly widely accepted as having certain advantages. That said, plucky little chaps, aren't they. Perhaps they are like fleas, able to pull 1,000 times their own weight? What load are they pulling, 5 tons?
Taking the urine aside, could I suggest you gentlemen consider alternative explanations to your sizist assumptions. The OP is clearly 2'6" and does things on a proportional scale
Curiously, 7 Welsh Terriers at a typical 9 Kilos will weigh about the same as my Rubes. You can see why I don't have my two on leads much, or if so walk them one at a time; combined weight of about 220 lbs or a tenth of a ton. You notice when one treads on your foot. Really should hook them up to a cart or use them for logging. They love the wood, although they will insist on trying to dig up every mole.