So blame the dog for equipment failure? Are you sure he started it and not the cat? I have seen a few times were it a bulldog got loose and the cur dog was actually the one yo instigate the fight but just ends up on the loosing end most times..?.....just my thoughts.
I am with Underdog on this one...
The cause is equipment failure. I own a game bred apbt and I am raising him to get along with my other dogs and all is well. They are friendly with each other so I am pretty relaxed about letting them run together. I also know what a pitbull is capable of so I am always around and watch for any behavior that can cause a problem and nip it in the bud. A lot of the times he is not the instigator but a pit can finish what starts...
I also keep my pitbull in his own kennel and have the latch as primary door lock but also have a dog snap so it can not open.
The root cause is failure to evaluate the condition of the chain and make repairs as needed...
just let that be a learning experience. Believe me I have made those mistakes before but I will keep a pit as long as I feel I need one... Just learning as I go...
I wouldn't get rid of the dog until I gave them a chance to get along...if it this incident is the cause of a rivalry then you might have to get rid of one...