I have a 19 year old mare than has always refused to load into a two horse trailor. What do I do to get her to load? A horse will typically try all her avoidance tricks when it comes to loading into trailers unless they are taught that there is nothing to be afraid of in the trailer. I got into training because we once had a horse that would put up a fight and then end up hurting herself or me in the process. She was 16 years old at the time and like your horse put up a big fuss when it came time to loading. I finally decided one day to spend as long as it takes to have her load into the trailer and be calm about it. It took 2 straight hours but the persistance paid off. After the 2 hours it then only took a few minutes for her to load the 2nd time. Then on the 3rd time of trailering and then after she loaded within a few seconds. All this was done without having to step into the trailer myself or use anything other than a rope and dressage whip.
The first thing you need to do is set aside a full day. It may not take a full day to teach her but at least you'll have the time for it. Work with your horse in having her do small circles around you. To get her going tap her butt with a stick , riding crop, or dressage whip as you stand at her shoulder and point with your other hand that is holding a lead rope in the direction you want her to go. After a while do this next to the trailer or building or fence where there is only about 3 feet distance between you and the imovable object. This way your horse will have to get accustom to going through a narrow space. Once she does this freely and willingly then start working with her at the back of the trailer. You then ask her to hop in using the same cues as asking her to go around you in a circle. If she tries going between you and the trailer then step closer to the trailer. If she backs up then give her slack, let her back up, and walk with her but as soon as she stops ask her go forward again. If she stops going forward give her a moment, pet her and then ask her to go forward again. Keep working with her till her feet are next to the trailer opening. At that point just pet her for at leat a minute then ask her to step forward again. If she puts a foot in the trailer then stop asking for the cue and pet her some more. If she takes the foot out no poblem just ask her to go forward again. If she keeps it there then give her at least 15 seconds of petting then ask her to go forward for the next foot. Keep repeating this pattern for each of her feet till all 4 feet are in the trailer. This is where it might seem to take a lot of time but as long as you are persistant, gentle, firm, and reward her with lots of petting or rubs she will eventually get in.