A black and white dog is going through an obstacle course.
A trainer is training two dogs for a show.
First sentence only references a single dog not two dogs. Not all dogs in obstacle courses are training with a trainer. Not all obstacle courses are part of a show.
exists e1 s1 s2 x1 x2 x3.(through(e1,x2) & n_course(x2) & of(x2,x3) & n_obstacle(x3) & Actor(e1,x1) & v_go(e1) & n_dog(x1) & a_white(s2) & Theme(s2,x1) & a_black(s1) & Theme(s1,x1))
exists e1 x1 x2 x3.(Theme(e1,x2) & Actor(e1,x1) & v_train(e1) & for(x2,x3) & n_show(x3) & n_dog(x2) & card_eq_2(x2) & n_trainer(x1))