So this actually happened quite a while ago when our rats were still young. We had gotten three girls that were from the same litter. They lived in peace, occasionally getting in little scuffles over stupid stuff, but never anything too violent. One morning my fiancee had went to feed them to find one of them dead.

It was not natural causes, it was a straight up murder. Her throat had literally been ripped out. I know rats can occasionally cannibalize a deceased cage mate, but this was not the case. She was dangling out of her hanging bed with her throat completely ripped out and the body was still warm when I removed her.

We never really knew why she was killed, and the two sisters still live together right now just fine.

What sparked me to ask this question was that I was actually watching the South Park episode the other day where Lemmiwinks kills his brother Wikileaks, and he did it in the exact same fashion, ripping the throat out. It made me think maybe this is just a common thing among rats and other rodents?