I always used to cry as a child when my mother sang "Sweet Little Alice Blue Gown". Whether it was the words of the song, her smokers' husky baritone or the clip round the ear she gave me I don't know!
Although it is terribly corny, I , cynic, that I am, always choke when singing "Old Shep" when he has to be (sniff) put down (gulp), and goes to doggy heaven (boo hoo).