I totally understand. I had to make that choice for one of the strays I was feeding when I moved. He drooled all the time and when he ate it hurt him. When the vet saw him she said his mouth was filled with sores and she was sure he was in advanced stages of the cat lukemia. I couldn't risk him being around my 4 or infecting other cats in the neighborhood. He was such a sweetheart all he ever wanted was someone to pet him and rub his tummy. Even at the vet's he rolled over for a tummy rub. So we all gave him lots of tummy rubs before sending him to the bridge. Rest in peace, Drooly my friend. I promise if I ever find your original owners, I will give them a swift kick for you!!!