I went out to the barn at about 6pm last night to, in theory, get Tristan's evening antibiotics into him and check on the bandage to see if there was any drainage/bleeding after the poking around we'd done that morning.
He ate his antibiotic pills when I mixed them in with some dinner mints, and then when I pulled him out of the stall I saw that he had managed to shed both his hoof boot AND the dressing on his foot and was standing barefoot, surgical site exposed. I yanked him out of the stall, wrestled the bandage back on at least over his toe, and heated up water to start flushing ASAP. I had left my sterile bucket & syringe at home (we were supposed to go to every other day!) and rinsed out the clean bucket we'd been using to mix his antibiotics, as well as the syringe from the antibiotics.
I picked out 2-3 shavings and a small piece of hay that had gotten into the hole, carefully brushed the shavings away from the rest of the hoof, and then flushed probably half a gallon of dilute betadine down the hole. Then I gently scrubbed at it with several iodine swabs, and then squirted straight betadine in, rewrapped with clean gauze, vetwrap, and elastikon, and pulled the boot back over.
I tried to get the smaller size boot on his foot, but it just wasn't going yet - still a little bit too much padding. I latched the larger boot as tightly as I could, and wound the elastikon over the hoof as tightly as I could, but still worried about him all night. I went out about midnight to check on him, and then again this morning at 7am before work. Boot was still on both times.
I checked his temp and felt for heat in the leg this morning; both normal. I'll flush and rewrap tonight and do so daily for the next week, and keep an eagle eye, but I think things are ok. I've got a call in to the clinic to make sure there's nothing else I should be doing...but I caught it quickly, flushed it out thoroughly, and he's still on his general antibiotics. I think we're ok. I'm still sick about it, but hopefully it won't impact his healing.