I'm on the latest version 0.0.86, and I took my horse and cart with me into the mine. Unfortunately, the game crashed (thank goodness it saved my progress!) and when I re-entered the save, my horse was nowhere to be seen. I have checked the whole map. So now I can't easily haul wood or ores. And I don't want to start over because I finally started making profit.
OK Never mind. I looked up a few posts and saw "My Little Savegame Fixer. I ran that and it reset my horse and wagon for me. I'm glad it works!