FLUTD

Hi, My cat names Jai, Male, 1 year and 1 month old has FLUTD. I have checked him already to the nearest vet. However, my other concern is his food, he was prescribed of a Royal Canin Urinary S/O (in a can) but due to the fast transition of food from dry, he doesn't seem to like it. He's not eating properly since the 1st day of the year and doesn't poop yet. Any help that I need? He's under medication  I need help. He needs to eat. 

He hasn't pooped in almost two weeks?! You were correct to take him to the vet. What medication is he on? I believe they make that cat food in dry food as well. Perhaps you could transition him more slowly or add water to the dry food.

The first reason why I brought him to the vet was his urine increase than usual, then the vet advised me that he has an FLUTD and he's under medication for 2 months. (today is the 5th day). The vet also prescribed him a wet "Royal Canin Urinary S/O" (But he's been eating dry pellets since he was little). So the transition of food was really fast. Doctor said that I should try mixing the wet food into a dry so he can eat, but still he seems not attracted to it and he's not even pooping? Any recommendation and help?