My farrier and vets seem to prefer a dorm/torb cocktail. Torbugesic (butorphanol) is a little better at “quieting the feet” without having them so knocked out that you don’t really want to be working on their feet. Doesn’t last all that long…like maybe 30-45mins and I believe you’d need to give this mix IV.
I have called my vet out to a farrier appointment for this purpose, similar to your situation. Horse is not exactly an angel getting his front feet done anyway, but the RF which has had a couple injuries and a lot of poking and prodding and injecting in particular. The last injury, broken splint, kind of rekindled his obnoxiousness. So, for his next shoeing after that, I just paid the vet to administer the cocktail when the farrier arrived. It was worn off by the time we got to the hinds, but he’s fine for those. Would I want to do that every time? No, but it got us through that appointment, and after that he was back to his normal, semi-obnoxious self.