Hit a rat once. Tons of the suicidal wee buggers down by the canal. It somehow missed my front wheel and was squished by the rear. The scream it made was blood curdling. I went back to put it out it's misery but it had obviously managed to crawl into the undergrowth, still screaming. There was no way I was hunting about in the pitch dark looking for an injured, and probably very pissed off rat full of disease, so I left it to its fate. The screaming was freaking me out. I still feel guilty about that.