Hi and welcome to YT
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As a nurse and also as an interested layperson, I've never ever heard of using flour on wounds. Why would you not use styptic powder?
You're amputating a *body part* here, so I would just beg you to PLEASE take these poor babies to a vet who can do it safely, cleanly, and properly. I'm very concerned that you'd come to a random online forum and trust that you'd get the proper and safe guidance here. None of us here are vets. If someone was amputating one of *your* body parts, would you be okay if they prepared by asking about it in online forums, with no practice or live guidance at all....?
In this day and age, you could also just leave the tails intact rather than putting them through this amputation. One of mine has her tail intact and it's stunning.