This was disgusting!

Okay so I had two rats , females, and one had a stroke or something and couldn't move anymore. The healthy one seemed to be leaving it alone for the most part. But I had been trying to feed and take care of the paralyzed rat to keep her alive and all seemed okay. So I put her into a pile of bedding on Cristmas night to go to sleep and played on the computer all night. I came back in my room at 4am and looked in the cage, and to my horror, the healthy rat had eaten part of the paralyzed one! It was disgusting and it horrified me. Is my rat going to kill any other companion I put in there? Do all rats act like this? Are they cannabils? ugh, it's so gross.....