How is my dog still alive?

I mean i believe in miracles but this is a fantastic miracle! Well i was reading an article about cats (weird..) and it said cats can die or get sick from eating chocolate like dogs, and i remembered once i left a chocolate donut in a box on a low counter and left outside really quick to water my garden and when i came back in it was gone, and my box was on the floor and the donut was gone i could only suspect my dog because she was the only living thing in the house, she ate a chocolate icing donut, now is this just a miracle or what? But yes im thankful my dog is still alive its been a happy year for her with no problems, she recently turned 3 years old! (: