Just curious, did you buy the rats or freeze them yourself? When I first got into the hobby I bought an entire batch of frozen rats from a big frozen rodent company that did what yours did. Never hurt my snakes but I had several explosions. I think for sure they were refrozen. I only feed from my own home grown stock now and never ever have an issue. My frozen rats look much better then any I have bought and never explode. However, I had a big girl pop the eyeballs out of a live rat once. Poor little thing, it was a bit small for her and she was in super feed mode.