There are many vehicles for your dog to pull. Two wheel wagons meant to hull supplies and 2 wheel riding sulkies. There are 4 wheel wagon and 4 wheel riding carts.

Look threw the links below and see what you like. There are a few things you will need to know first.

The vehicle must fit the dog, especially on a 2 wheel cart. The shafts must come to the center point of the shoulder and be level back to the cart.

Here are some links to some great carts and wagons for your dog

Tonys Trailors, He also makes 2 and 4 wheel dog carts http://www.tonystrailers.com/dog/

Sierra KENNELS dog cart 

http://www.sierrakennel.com/

Dog Works

http://www.dogworks.com/