Young Californio kid I rodeoed with in the 70s trained spayed bit mules in the old bridle horse way starting with a bosal and working down in size to a pencil then letting the mule learn to carry the spade before he ever put reins on it then 4 reining to the finish took about 2 years but what a joy to watch a finished one, you could hardly see his hands move on the reins but those mules would put on a show not to be believed. His were all about 15 hands with very fine heads. Looked almost lie a QH with long ears beautiful animals.
