They also must be a dog the other dogs are willing to follow. The dogs behind the leaders are the strong pullers. The dogs nearest to the sled are called the wheel dogs. The wheel dogs are the most loyal dogs. They must also anchor the sled.
Mushers try their dogs in many positions before racing to find out where each dog works the best.
There are many kinds of commands in the Iditarod. Dogs have to have special equipment such as special booties that protect their paws from sharp ice and snow. The dogs also need an extra gangline in case the other one breaks. Dogs need special coats. One of the coats they need keeps them warm and the other coat reflects the sun so they're not too warm.