I also have a 10 year old cat who had exploratory surgery because she was vomiting. They thought it was Pancreatitis
, then an x-ray and u/s showed a thickening in
the colon so that is when we scheduled surgery. This is not Mega Colon but IBS, and I treat her with 1/8 tsp Miralax in her morning wet food and her evening wet food. She is on a diet pf Z/D prescription wet food and dry, and takes Budesonide (formulated as a liquid) every day.