Dog carting, or sulky driving, is a sport in which one or more dogs pull a two-wheeled manned cart (the "sulky"). If the cart is built well and the harnesses fit properly, there is no harm or undue strain on the dogs.
Fit your dog with a comfortable harness, since he or she will be pulling your weight as well as that of the cart. The harness should have plenty of padding made of soft material. This padding not only relieves pressure but also avoids soreness that could be caused by a raw harness rubbing against the dog's skin.
Building a suitable frame for the sulky can be expensive and time-consuming, so some riders prefer to use bicycle "trailers" that parents use to pull their children while cycling. They are made for pulling and have seats already built onto the frame. To use one as a sulky, strip the trailer while leaving the chassis, wheels and seats. Since there is a shaft on one side of the frame, determine how it is attached and, using another shaft, copy its connection on the other side.
Find two strong aluminium poles to be used as shafts. They should fit snugly over the ends of the trailer shafts (they can be secured by aluminium bands) and run along your dog's body, ending slightly back from its chest. They must be long enough for your dog to run without any hindrance and far enough from its front leg that he will not poke himself when he stops. It will also keep him from being poked in the side as he makes a turn. Place the shafts through the harness loops and secure them to keep them from slipping forward in the loops. This will allow your dog to back up or stop the cart.
Attach a long leash to your dog's harness in order to moderate his speed and movements. This should be attached to the metal rings on either side of the harness yet be clear of the shafts.
Work with your dog to get him used to pulling the sulky. It may take time to get him used to his role, so patience is a key factor. Do not give your dog more weight than he can carry comfortably. The shafts should be parallel with his body and not slanted toward it. When he gets used to pulling the sulky, make any commands firm and consistent so the dog will not become confused.