My rat masie has been sick with a respiratory infection for a couple weeks now, we have been treating her and she has seemed to be getting better. Tonight I went and found her dead laying underneath her sister Eevee. She had been completely disemboweled. Her sister Eevee has never been aggressive and is pretty elderly, so I don't think she did this. There was no blood anywhere else in the cage except for where she was laying. Is there something that would do this? Would Eevee rip her sister open even though shes never bitten or hurt anything ever in her life? Any advice would be welcome, I genuinely have no idea how this happened and have never seen anything like this before.