Saying final goodbyes to pets

In the last ten years, half the time when I left my mother's place and saw the dogs staring at me, I would give what may be my final goodbyes and wondered if I would ever see them again. I am aware of mortality. Especially after one 3-5 year period of my life as a teenager in which, whenever I got back from vacation abroad, I would learn a pet or friend had died.