Animal aggression in no way correlates to human aggression, they are two totally different things. Stop and read that again!
Most, if not all, bulldogs have a certain amount of animal aggression wired in...they are bulldogs after all.
Despite the popular belief...a good bulldog is not that easily replaced.
No bulldog should ever be left unattended/unsupervised with other dogs.
It's your responsibility to make sure that pups and small furries can't get into her run/chainspace.
Now, go back and read the first sentence...
Scott for the win.
If the small dog went in to the kennel and started a fight,who do you blame. A dog will only take so much. If pushed most dogs will fight. Maybe they were just playing around. Who knows. If you are worried,get rid of the pit. It is our job to keep dogs properly contained.