Our old boy is 16, on Tuesday he ate only a tiny bit, on Wednesday morning I took him to the vet who did bloods and said he had an overactive thyroid and prescribed medication, also prescribed pain medication because he teeth aren't good. He has a heart murmur which we have been aware of for a few years and the vet scored this as 4/6 and said that she would not recommend anesthetic for his teeth to be dealt with. They admitted him to be put on a drip as he was apparently dehydrated, but gave him pain meds, he apparently ate a big bowl of food and was discharged without the drip. Since then, he has eaten very little, wont touch his normal food, wont touch any of the soups, pates, tuna etc which I have bought trying to tempt him. He had a poo in his litter tray yesterday and had a big wee today and is affectionate and reactive but not his normal self. He is tolerating his meds and we have started syringing him some water (very carefully) to keep him hydrated. He ate a tiny bit of roast pork which I hand fed to him yesterday after he refused everything else and today he has only eaten 5 dreamies and a little piece of chicken which I broke up into tiny pieces. I have tried warming up chicken a little tonight but he isnt interested. We are taking him back to the vet tomorrow but I really dont know whether we should try other treatment, in patient treatment or whether it is time, both the thyroid meds and pain killers apparently can cause a decrease in appetite (according to my google searches). He is absolutely loved and adored since we got him as a tiny kitten and he walked to the door of his birthplace as though to say take me home please.