We had a dog called Stanley when I was born. I grew up with this dog from birth. He played with me in my playpen, went for walks with me - basically he was by my side at all times. I loved him so much. When I was 12, he died during a surgical procedure. I didn't even know what death was at that point in my life. I didn't even know he could be gone forever. I remember my parents telling me that, "Stanley died" and I was so confused. Once I realized that he would never be returning I cried and cried and cried.
I'm in my mid 30's now, I have had other pets that have passed on (and I miss them dearly) but, I still cry for Stanley when I think of him.