Re: Very bloated weanling rat! Whats Happening?!
Just because one has doesn't mean they all have it, correct, but do you want to continue with these genes? Once a line has been proven high risk for megacolon, it's best to find new genetics. Especially since you didn't even breed the male to another high white. I'm not saying just because one popped up to get rid of the male, but honestly, if it was my colony, I would not breed him again. You can give it another shot and see if maybe this baby is just unhealthy and a once in a lifetime fluke, but I'd be cautious and pay attention to the others.
Remember, while most cases of megacolon appear before 6-8 weeks, there is late onset megacolon, which has been reported at 8 months.
Best bet is to euthanize the baby now, it only gets harder to watch. So sorry for this, I know how tough it can be to deal with megacolon babies. I ended up losing an entire blazed litter that I rescued from megacolon.