Most horses have to be desensitized to them. Some horses don't even like the noise so you may have to get them used to that first. I often go into their stalls while they're eating and just turn the clippers on so they'll get used to it while being distracted with something else. :) The first step is to get your horse used to you touching their ears all over. Stroke thier ears, rub your thumbs inside of them, etc. It's more tolerable if you follow the direction of the hair. It's very important that you don't let him jerk his head away from you. Hang on to his halter and keep your hand on his ear and then pull away when he stops struggling. (can be hard if he's bigger). Then with the clippers turned off rub them all over his ears, face, etc so he'll get used to those touching him. Then, turn the clipper on, but touch the clippers to the back of your hand as you rub your hands all over him. -it greatly diminishes the tickly vibrating feeling but he can still feel it a little bit. Then rub him with the non blade end of the clippers so he can feel the vibrating directly but you're not cutting any hair. Then the last step would be to actually use the blades on him. Short spurts at a time wtih lots of treats when he does well so it turns out to be a positive experience!