The point is that killing it yourself *IS NOT AN OPTION!* Because there is no way to guarantee complete efficiency. There are a thousand and one ways to kill something, yes, but the thing is to do it correctly. Most people will not do it correctly, thus prolonging the pain. Every person ever brought up on animal cruelty charges for that will tell you the same thing, they thought it was dead.
The point is that because there is no way to guarantee a clean, swift death at home, the OP [and *anyone* else reading this] needs to take the animal to a Humane Society, Animal Shelter, or E-Vet. Most of these places will humanely euthanize an animal to end it's suffering at no charge, or for a small donation. E-Vets are obviously open after hours, so that's not an excuse.
Allowing any animal to just lie there and slowly die is not an option, either. Action must be taken to end their suffering. Ending it yourself is not the answer.
Rattikins : You need to learn what 'rhetorical' means. Lilspaz was proving a point of how difficult it would be to kill a grown rat yourself. As for you not advocating the OP [or anyone else] not killing the animal themselves, you sure could have fooled me. I had to go back and search for where you mentioned taking the animal to the vet. Everything else was how the OP [and anyone else reading this] should take action, be an adult, and kill the animal themselves.
There a is a difference between 'yucky' and having to live with what is basically a traumatic experience. Having to end an animal's life yourself is a *very* difficult thing to do. Going by your indifferent responses, I take that to mean you've never had to do it yourself. Lilspaz was trying to save the OP [and anyone else reading this] the trauma of having to do that. She advocated taking it to an authority that could not only ensure a clean death, but someone who's job that is and is used to such ordeals.