My cat, who is male about 4 yrs old, will not eat wet food or fresh food of any kind. I have always given him really good grain free dry food which he tolerates. The vet recommended he eat the urinary food that they sell which I thought would be good. I mixed some with his regular food and he ate it quickly but soon after threw up all his food several times. In addition he threw up yellow stuff a few times which was not good. I was almost ready to take him to a vet but I decided to wait.
Not wanting him to get dehydrated, I made some peppermint tea and also had a commercial aloe/coconut water (not milk! ) which has a little sugar. I slowly fed him from the side of his cheek with a large medicine dropper (the kind they use to administer liquid medicine to babies). I fed him only 2 dropper fulls of each to see how he would react. He took it well and did not regurgitate. I did this about 2-3 times in about 2-3 hr. increments and then when I returned home in the evening.
In the meanwhile, the next day I did administer 1/8 of a pill the vet had given me another time to increase his appetite because I knew it was important for him to eat. When I came home he did eat the controlled amount of food I had left for him of his usual dry food. No messes but I was concerned because the litter pan was dry. He is an indoor'/outdoor cat but I didn't want him out because of the problem. I fed him some more of above water as I described and took him for a short walk outdoors on a leash. He didn't go and I was still concerned.
I came back and gently massaged his belly and area around the kidneys. Shortly after he finally did urinate in his litter box. I'm not concerned (yet) that he hasn't pooped because he really did not eat until today but he definitely looks better.
I definitely recommend pure coconut water for hydration-- best unsweetened but a little sugar shouldn't hurt unless diabetic. Give in small quantities as I described in order to prevent dehydration. Coconut water has minerals and acts like "pedialyte" but is much better for you. It worked well for me.