Unforunately it does happen

My boa was always fed live and I did for two feedings after I rescued him as I was in the process of learning myself. Well the rat bit him. It wasn't bad at all and only left a like 1/4 inch little puncture that I cleaned daily until it healed, but still it could have been a lot worse. After that I switched him to F/T. He didn't eat for two weeks, but I didn't let up as he was an adult and wouldn't lose that much weight by not eating once or twice. He did end up switching after two times of refusing.

My baby ball python was on live when we got her. We switched her over to F/T after her second meal with us. Then we gave her two F/T mice feedings before switching her to rats.