sorry for your loss, hon
mine is almost 19. he's been sick since he was 11 and is slowly on his way downhill, he's on three different meds three times a day, he's lost his hearing, has trouble with balance sometimes, and yowls when there's no one with him to keep him company. there are periods when i have to give him sub-Q fluids everyday.
but he's not in pain yet, and he's still the same incredible personality who's been with me through thick and thin for 19 years. when i eventually lose him, i know it will be unbearable - so i feel your pain