Snakes - Live Prey vs. Prekill
There is a very common misperception among people, even among many snake hobbyists, that snakes must have live prey. This is not usually true. In the wild, snakes, like most other carnivores, will usually take any opportunity to get a free and easy meal, and will not pass up a freshly killed prey animal if they happen upon it. In fact, snakes have been known to eat a fair amount of carrion which has been dead for some time, and the stomach contents of wild snakes often contain prey that must have been in an advanced state of decomposition when it was eaten. Thus, although your snake may prefer to eat live prey, which it kills itself through constriction, this is not at all necessary for the health of the snake. In fact, it is best not to feed your captive snakes live prey at all.
Most snakes which are kept as pets are constrictors. In this method of killing prey, the snake will seize the animal in its jaws and very quickly wrap its body into a series of coils which envelop the prey, squeezing it with powerful muscles. Contrary to what many people believe, a constricting snake does not crush its prey to death; rather, the snake will tighten its coils every time the prey animal exhales, which squeezes the prey's chest tighter and tighter until it can no longer inhale and smothers. Once the prey animal is dead, the snake will use its tongue to examine it until it finds the head, and will then proceed to swallow the prey nose-first.
There are several reasons why it is best for the snake hobbyist to feed pre-killed prey exclusively, but the most important is for the safety of the snake. Mice and other rodents are fast, smart and have lethal teeth. Snakes, on the other hand, are slow, stupid and can only kill by constriction. If, for whatever reason, the snake decides that it does not want to eat a live food animal, the prey animal is very capable of turning on the snake and killing it. Even if the snake is willing to feed, it will very occasionally make slight mistakes in its attack--it may grab the rodent by the wrong end, or it may miss in its initial strike, and even a slight opening is enough for the mouse to counter-attack. Live mice will fight for their lives when they are seized, and will bite, kick and scratch for as long as they can. Every experienced snake keeper can tell stories of snakes who have been severely bitten and injured by live food animals, and most snake collectors have at least one snake who has the scars to prove it.
In most cases, feeding pre-killed food to a snake is a simple matter of dropping a dead mouse or other rodent into the cage and waiting until nature takes its course. If you are using frozen mice, be certain that the mouse is thawed thoroughly all the way through; if the center of the mouse is still frozen when the snake swallows it, it can produce severe intestinal distress that might even kill the snake. One good way to thaw a frozen mouse is to pop it in the microwave for a minute or two on low power (don't tell your housemates you are doing this). Another good method is to place the frozen mouse in a ziplock plastic bag, and then place this in a pan of hot water for about fifteen minutes. Most snakes will prefer to eat in the dark, just after nightfall, and many snakes will drag their prey into their hide box before swallowing it. Some individuals will prefer to leave their prey sit for a few hours before they will eat it. A few snakes may prefer to constrict the dead prey first (apparently to make sure it is dead), but most will simply grab it in the jaws and start swallowing.
Some snakes, however, may prefer their prey to be moving before they will take it, and this can be accomplished with a pair of long-handled tongs or forceps (never touch a dead mouse with your bare skin when you are feeding a snake; the snake may mistake your hand for a food item and bite you). Using the tongs, hold the mouse by the tail and dangle it gently a few inches from the snake's face. After a few exploratory tongue-flicks, your snake will seize the food and go through the motions of constricting it. If your snake seems reluctant to feed, lightly touching the food item to the snake's nose may be enough to trigger the feeding response. If your snake repeatedly strikes at the mouse and then quickly withdraws, it means he is not hungry. Try again in a day or so. (Please note that most snakes will stop eating for a period of several weeks before they shed their skin.)