>>2543760dogs used as utility are draft animals, meaning that they pull weight behind them as opposed to bearing the load on their body. A better option is a travois or small cart. The most you should load on a dog as a pack animal is probably dried food and a small silicone bowl or something, just judging from the shape of their spines vs an actual pack animal such as an ox.
Would recommend reading the difference between draft and pack animals, it's actually quite interesting.