I had the most spectacular explosion of mouse guts the second time I ever fed my BP...I swear it looked like a horror movie. It still happens every now and again, usually from overheating with the heat lamp (as the poster above said) or when the mice have been in the freezer a while. It's gross, but it doesn't seem to bother my snake at all, and sometimes I think he even goes faster for the ones that are leaking guts!