A Crappy Lesson

Boy is 12.
2 months ago family gets dog for boy because he has ADD and the dog will help us teach him consideration for others.
Dog pees on carpet a few times in the last two months.
Boy has difficulty learning to treat the dog with respect.
Tonight he is (lightly) smacking dog on the sides of the muzzle while making an annoying noise with each smack.
Again we are telling the boy to stop it and be kind to the dog and treat him with care and consideration.
Wife and I are in the bedroom talking.
Boy suddenly yells in a panicked voice.
The dog has taken a shit on the carpet in the boys room.
The dog has never crapped in the house before.
He would stand at the door and whine before pooping in the house.
NOT TONIGHT!
Why?
My theory - He's teaching the boy a lesson.
Treat me like shit and I'll shit on you!
Who agrees or disagrees with this assessment?
mykl