Whoa, my cat has had colitis for two months, since I switched him from the Nutro Natural Choice Indoor to the Nutro Natural Choice Indoor Weight Management. We've been looking for every possible solution, and Flagyl was given but didn't help. I was starting to suspect the Weight Management food; but I had studied the ingredients and they looked so similar to the regular food, I doubted whether it could be the cause. I also noticed that the Weight Management pieces were much harder, and thought maybe that was it... that the hard bits were irritating his digestive system.
It sounds like you guys may have solved my problem.
He doesn't exhibit any other symptoms of a food allergy, though. No scratching, etc.
From what you know, would it be all right to switch him back to the non-weight management Nutro Indoor? I'm a bit confused, since the regular Indoor also contains the soy concentrate, and he was regular and colitis-free on the regular Indoor.
Also, the Weight Management food made him go from slightly overweight back to a perfect weight. Maybe I could try the Nutro Max Cat Lite instead. If I know that soy is the problem, I can just look for that and avoid it.