My favorite pastime is browsing through vintage photos of dogs. One of my digital haunts is the Library of Congress. I came across this photo titled, "Man and dogs on a rail cart trip from Shelton to Nome, Alaska."
I expected to see dogs pulling something. Instead it features a bunch of happy dogs piled on a rail cart heading towards Nome. Notice the writing on the photo: "Coasting on a dogmobile trip, from Shelton to Nome, Alaska, July 28, 1912."
When I enlarged the picture, I saw that all of the canine riders are typical husky-type sled dogs, with the exception of an English Setter on the seat. Setters were often used as lead dogs. That's probably a driver and his dog team, with his lead dog on the seat next to him.