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My name is***** and I am sorry to hear that your kitty is having bladder problems. It sounds like you were sent home with the best medications for him. It also sounds like you are on the right track nutritionally as canned food with added water is the best thing for him.
As for how he is doing right now, I would not wait more than 12 hours from the time they expressed his bladder to when I would expect to see him urinate again. If he hasn't peed in 12 hours then I would have his bladder rechecked. It is common for male kitties in this situation to become blocked and be unable to urinate. This, of course, is life threatening.
In the long term, he will do very well. Bladder problems are very nutritionally related and can be managed well with diet and sometimes additional medications.
Does this help? What other questions do you have?
How is your kitty this evening? Is he urinating normally now? Did you end up taking him back to your vet? Do you have any more questions for me?