My cat had a PU in the fall. He didn't really eat or drink anything and was really, really lethargic four days post op. I took him back to the vet and he received fluids via IV for dehydration overnight. After that, he was fine. It was still a struggle to get him to eat though until his stitches...
I'm wishing Happy well! I can only imagine the stress and worry you're feeling.
My cat Simon had a PU in the fall. His vet assured my Mom and I that he made the new opening so wide that he could theoretically place not one, but two catheters side by side in it. Not that he would, but after...
I give my guy, who had kidney and bladder stones, Purebites dehydrated chicken or ocean whitefish treats. I asked his vet first and he okayed them as long as they're given in moderation of course. Simon gets them maybe once or twice a week.
I'd also recommend Purebites. My little guy also has FLUTD (had calcium oxalate stones removed and a perineal urethrostomy in October and has been doing great since!) and the vet said no other food other than his RX wet and dry Royal Canin Urinary SO. I found Purebites a few weeks ago though and...