I just get upset sometimes when people think so much more of thier snake then the prey it is given. People tend to get soo angry at the rat, when in reality, all it is doing is what any of us would do in the same situation. Imagine you getting bit and wrapped up in a giant anaconda or something like that. Are you going to just lay there and let it eat you? Of course not, you are going to fight with all you have in you. Rats and mice are no exception. Realize that they are fighting for thier lives too, and that is where the damage to your snake happens. Even worse is a rat that has been struck at, but the snake missed. THEN you have a really pissed off rat, that will fight out of fear, anger, and adrenaline.
Lets not forget that although rats and mice are part of the natural feeding chain, that doesn't mean that we have the right to treat them badly or cause them undo pain and suffering. Cutting thier teeth out so they cannot react to their natural defense mechanism is cruel punishment.
The best thing for everyone concerned--your snake, your prey item, and you--is to humanely kill the prey before-hand.
Yes, there will always be a debate on whether certain snakes will only take live. I think, for the most part, that is a load of crap. I took in a 3 year old rescue a few months back, and it had been fed live its entire life. I offered pre-killed the first feeding, and it took it no problem. Remember, you can make any pre-killed rat appear to be alive with a long pair of hemo-stats.
Usually, the ones that say that thier snake "will not take anything other then live" are just making excuses for their selfish actions. I beleive that you can turn ANY snake from feeding live to feeding p/k. It takes time.
On a side note, think of these snakes in the wild. Sometimes, it may be weeks or even months before a snake finds a rat of mouse to come walking by it. Out of survival instinct, if a snake comes across a dead prey, it will eat it!!
As seen on a bumper sticker--"My snake ATE your honor roll student"