You would never think of making a deer into a working beast of burden, but semi-domesticated reindeer in Russia and Northern Europe have been used to pull sleighs for a long time (Santa Claus notwithstanding). Could you get a moose, the largest deer species, to work for you? Minnesotastan found a picture of a moose working as a beast of burden, and found it was a Photoshop job. But in researching one photo, he found quite a few other pictures of moose being used to pull wagons. See them at TYWKIWDBI. Link