Being a veterinarian, I had been called to examine a ten-year old  Irish
Wolfhound named Belker. The dog's owners; Ron, his wife Lisa and their
little boy Shane, were all very attached to Belker and they were hoping
for a miracle. 
 
I examined Belker and found he was dying of cancer. I told the family
there were no miracles left for Belker and offered to perform the
euthanasia procedure for the old dog in their home. As we made
arrangements, Ron and Lisa told me they thought it would be good for the
four-year-old Shane to observe the procedure. They felt Shane could
learn something from the experience. 
 
The next day I felt the familiar catch in my throat as Belker's family
surrounded him. Shane seemed so calm, petting the old dog for the last
time, that I wondered if he understood what was going on. Within a few
minutes, Belker slipped peacefully away. The little boy seemed to accept
Belker's transition without any difficulty or confusion. 
 
We sat together for a while after Belker's death, wondering aloud about
the sad fact that animal lives are shorter than human lives.

Shane, who had been listening quietly, piped up, "I know why."

Startled, we all turned to him. What came out of his mouth next stunned
me - I'd never heard a more comforting explanation. 
 
He said, "Everybody is born so that they can learn how to live a good
life - like loving everybody and being nice, right?" The four-year-old
continued, "Well, animals already know how to do that, so they don't
have to stay as long."