This summer as in now or are you the opposite hemisphere and going into winter right now?
First - ALL my empathy. My horse had one (1!) power float in her life and that caused her to completely lose her shit over every mechanical buzzing sound on the planet - drills, clippers, toothbrushes (yes, I tried a frickin’ toothbrush as a starting point to get her over her fear.)
10 years later she can be clipped with small battery clippers and can ‘cope’ with a horse nearby getting clipped with any size of clippers in a safe place (her stall or her favourite grooming slot) as long as she is not tied (and she ties like a champ.) She will not get power floated again. Her first vet was absolutely adamant about that because he saw her break through her tranq after she’d just been perfect for a hand float because some other horse was getting a power float. That vet moved on to small animals (
) so it’s been a bit of a struggle each year but I remain firm and eventually find someone to do her. Anyway, tangent over.
If you are in winter - blanket, blanket, blanket. Ride with a way heavier cooler (yes, cooler, not just a quarter sheet - just drape the whole thing over the saddle) than the temperature calls for and watch the hair start to fall out. Next autumn, start rain-sheeting and blanketing this horse far before any other horse, far before the horse really needs it. Keep the horse just this side of too hot (sweating) all winter. If you don’t cave and continue from beginning of autumn straight through winter, the horse will come through with a lovely short coat.
Note, there are people that will argue with you about the blanketing thing. Tell them it’s not their horse and you’re just trying a thing some crazy Canuck told you about that has worked for her can’t-be-clipped horse for 10 years. Do not listen to their ‘reason’ about daylight hours and yada yada. They’re wrong, but they don’t want to hear that
and in all fairness, I didn’t believe it until I got desperate and tried it. Do be prepared for the horse to start shedding what little winter coat it gets about 2 months ahead of every other horse. But hey, it’s short and sleek and no big deal - not like woolly mammoth shedding that many unclipped horses go through in the spring.
If you’re in the same hemisphere as North America - those hand clippers someone posted a video of may be worth a shot. And that said, maybe some blood work before purchasing the clippers because pretty much no horse, especially a TB, in NA should be too woolly for showing right now in the middle of July.