When our rescue kitty Spike was a little over 18 yo, he started loosing weight and having symtoms of his renal failure. Things had been pretty goor for the last 4 or 5 years and at 16 1/2 he even made the trip to AK. He had several problems but he had been happy and never cried or did anything unusual. I knew that there was something wrong and took him to the Vet, he had been eating but losing weight, scat was pretty normal but something was wrong. Dr. Cartwright looked him over as I told him what was happening. I told the Vet as far as I was concerned, money was no problem if it would get him back on his feet. The Vet looked at me with a tear in his eye and said "It is time". The Vet really liked Spike and was amazed at his coat, even at 18 it looked smooth and glossy, like a synthetic wig, polyester like. He left the room for a few minutes to let me say goodby...
I still cry and his ashes are above the computer and we talk when things get really bad. Today they were really bad. I don't know how to comfort you, I just know you know, they know and there is no guilt.