In polar climes, where snow is common, dogs become useful for transport. Sleds may be made from wood or from bone and hide; they are tied or sewn together, because flexibility is critical to prevent the sled from shaking itself apart.

A sled must be at least five feet long. It weighs five pounds per foot of length, and has a capacity of one hundred pounds per foot. This capacity includes the driver and any passengers, plus cargo and supplies.

Any number of dogs may be used (maybe some bonus from Animal Handling?). Each dog requires a stone of food per day, often fish supplemented with fat and a small amount of grain. It's generally fed to them as a soup so that they get water at the same time, and so that diseases and parasites are cooked out of the food.

Dogs may pull up to their body weight at their standard movement speed. From their body weight to double their body weight, take the dogs' speed, subtract 120' from it, then subtract double the result from their speed (so dogs with speed 150' normally will have speed 90', and dogs with speed 210' will have speed 30'). This represents that the slower dogs are built for strength and thus are better with heavy loads.

A "racing sled" with dogs of 210' movement will have a movement rate of either 15 miles per hour if lightly loaded or 2 miles per hour if heavily loaded. A "freight sled" with dogs of 150' movement will move at either 9 or 6 miles per hour based on weight. (Note that there's some rounding involved here to make it work best with 6-mile hexes)