Our cat 'Cartes (short for Rene Descartes) had been sick for a while. He had lost a lot of weight over the last several years and was becoming more and more lethargic. This morning he started constantly spitting up. I took him to the emergency vet; he was down to six pounds (a loss of a pound and a half in two months) and his white blood count was quite elevated. He was clearly quite sick, and we decided the humane thing was to let him go.
Cartes was Cecil's first cat. She got him when he was born and going to U of MD at College Park. So he predates me. One of the things that clued Cecil in that maybe I was someone special was how quickly Cartes took to me. He was sitting on my lap the second or third time I came to visit, and he was not a people cat (and I was not a cat person, for that matter). He had the loudest purr of any cat I've ever known. We'd hear it every night when he snuggled us in bed.
All four of us - well, five of us, counting Tepi - will miss him a lot.