I’ve been wondering about this since Daisy’s trip to the vet for a micro enema a month ago. She’d gone about 51 hours by the time she had it, and did a good big soft poo about 20 minutes later. She hadn’t strained or as far as I know tried to do a poo at all. She urinated normally, and ate and drank normally. When the nurse examined her she couldn’t feel anything hard inside, and said there was soft poo in her anus. It makes me wonder if megacolon has that effect on some cats, and whether some can indeed go longer than the 48 hours recommended. I was worrying about it again last night when she hadn’t been for well over a day, but thank goodness she did a good big one this morning - 36.5 hours since the last!