To potty train your mini horse try to reinforce outdoor elimination on cue and reward him for doing the right thing with little treats. From the beginning you should ignore any indoor elimination behavior but pay attention and take your mini horse outside as soon as he shows any signs of trying to eliminate in the house. You should practice this for at least a few weeks, maybe longer, depending on the horse. If you are patient and persistent enough, your horse should learn to wait for you to take him out when he needs to relieve himself. Over a period of several weeks, your horse will learn to wait to relieve himself until you take him out for a bathroom break. As your horse learns to go to the bathroom outdoors, you should begin to gradually wean him off of his treats that he used to get as rewards for going to the bathroom. Try to wean him off these treats gradually.