One Smart Dog?

Two dog owners were bragging about the intelligence of their pets. "The brightest dog I ever had," said one, "was a Great Dane that used to play cards. He was a whiz at poker, but finally a friend complained about him and I had him put to sleep." "You had him put to sleep, a bright dog like that? A dog like that would be worth a million dollars." "Had to", he replied, "Caught him using marked cards."
Originally published November 14, 2002.