Friend of mine had her dog in heat in its crate in the house with a male that was not in a crate. It was her roommates male and he was not fixed. They thought a metal crate would be enough. She came home one day and she had broken out of the metal crate and was pregnant.
No idea what type of kennel you have, but things can happen. Where there's a will, there's a way.
I just turned it on . I was looking bird dogs in the butt this morning.