Thanks for the welcome and information!
I feed Zeus 5/8 cup of dry food every day and at night he gets a little more than a tablespoon of wet food mixed with a dietary supplement called Lysine, which is supposed to hinder the replication of viruses in his system. This is the same diet he was on at the rescue I adopted him from two weeks ago, including the Lysine. I should mention that Zeus is a little overweight. He is currently about 17.5 pounds and should probably only be about 15 (he is a bigger framed cat.) The first week I got him I had the vet examine him and he received a clean bill of health. The vet recommended that I keep him on this diet for now since he is getting a lot more exercise and is not being free-fed anymore.
Since I have seen him drinking from his water bowl on many occasions, I would be very surprised to find that he is dehydrated. His behavior hasn't changed at all, so I guess I will just keep hoping to find a present for me in his litterbox for one more day before I call the vet or do something else to help him.