My animated preloader

I can’t get the as right for this dog chasing scene I created.
I want to make it so when you click on the stop button you get a still image of the dog without the chasing animation in the bg and then when you click it again it goes back to just the dog chasing tail. Then I want to make it so with each subsequent click a new still image of the dog.
Can som1 give me a hint about how to go about this ?