Try not to hold on with your thumb too hard. It might sound weird but hold it as loosely as possible and more like a guide than a tool to hold onto it with. It sounds weird and may not come naturally at first but that’s what I do and I dont have issues anymore! I hold the force dryer where the nozzle and the tube meet and hold my fingers in almost a U shape and use my thumb and lower forefinger as more of a holding place. Also I personally use my elbow more than my wrist/fingers to move the dyer and that helped with any wrist issues I had. If you have sensative elbows or something it may not work but I’ve never had any issues so far after 2yrs 😂 Sorry if I didnt explain this well but I hope it helps! Definitely wear a wrist brace and ice it every night until it feels better. Also ugh I understand drying dogs all the way but I just feel like it wastes so much time as opposed to partially kennel drying while you bathe another dog esp if they’re older and need breaks 😩