How old is he? Megacolon doesn't show up until weaning. I just lost a rat to megacolon. I aquired a siamese female that was already gravid. She had two high whites, one a dalmation, the other a banded blue blazed. The blazed did not get megacolon (probably carries it though) and the dalmation has it now, she is about 4 1/2 weeks. I will be taking pics and then feeding her off. She was a sweet pretty girl and i am so sad about this horrible disease...