Asking for advice. I have a 17 year old neutered cat who suddenly stopped eating and drinking. [View all]

After a couple of days, I took him to a vet, concerned he was having a health crisis. He has lost weight from his last visit one year ago, from 9.5 pounds to 7.8 pounds. She did a full blood panel and found nothing wrong. Kidneys, liver, thyroid, pancreas, glucose, everything is normal. She sent me home with a potassium supplement.

A couple days later, I went to another vet to get a second opinion. Same test results, no treatment recommended, but they did give him some fluids because he is dehydrated.

I have him at home and he is eating very small amounts, and I have found some small amounts of urine in his litter box, but I can see he is not getting nearly enough food and water to sustain him. As for the cat, I see no great distress. He is active and social and seems happy, purring when he is petted and walking around with his head and tail held high. No vomiting, but very loose stools. And thin. I can feel him getting thinner and bonier. He shows an interest in food, runs to get fed, but when I put his food down, he sniffs at it, maybe takes a nibble, then walks away. I've tried his favorite foods and lots of treats, but can't get him to eat more than a few bites.

Any ideas? I'd appreciate any suggestions. I am at my wit's end.