personally I don't like to feed FT rodents that look like that. My thoughts on it, it looks like rigor to me, which means that it was dead for a while before it was frozen. Just IMO, I could be wrong. I work in a hospital, and double as the morgue attendant, but I'm sure there are other things that can cause that. Personally i wouldn't risk it. That's why I started breeding my own rodents. I know they are safe. LOL