I hope you're not feeling too guilty about it. Many people just don't know these things and when you buy stuff in the store you kinda sorta expect it to, at the very least, not be so harmful.

One of my cats had chronic diarrhea when she was a kitten and even after vet visit it didn't stop. That's why I started reading about feline nutrition and learned that cats need basically two things: meat and water. That stupid special diet food didn't help, of course, it was dry food with stuff they didn't need. We switched to better wet food and cut almost all their dry food and all the issues were gone. My boy started peeing more which is very good, especially for male cats (they get UTI's very easily). They also both started pooping less, which is very logical if you think about it. All the non-meat filler.. well they can't digest it, so they poop it out. Now they eat 100% meat and they poop once every 2-3 days, and in way smaller quantities. Oh and their fur became way more full and much softer too. They just look healthier.

During my search for info I found this website. It's a great thing to read for every cat owner. It lays out the info in a very logical way en it's easily understandable. I'd say everyone who has cats should read it.

My cats are pushing 11 now (they're siblings) and have zero health issues. I'm so happy I figured it out when they were so young. Still, I think it's terrible that so many people just don't know/learn these things and have the best intentions but then still end up hurting their own cats, because the stuff they buy is simply bad. But I guess pets aren't really a high priority for lawmakers, so I doubt standards for pet food will change any time soon. This is why I try to spread around info a bit.

Your cat is very lucky boy, hopefully he still has many years. :)