With ten years of supervising a dog park, I've dealt with many of these kinds of fights. Several things went wrong in this interaction. You had a dog on lead, in a off leash park(The dogs weren't playing on a level playing field). Dogs are constantly checking for who should be alpha. A dog on lead has a need to protect his master and project power even if it is very subtle (check for that subwoofer bass line growl, barely audible). This would be especially true in a ten month old intact dog just coming into his hormones. To other dogs, a dog on leash is considered inferior in pack ranking and they will come over to investigate. If you are about to enter a off-leash area and spot a staffordshire or any other bull terrier type that you haven't met before or don't personally know his history, I would keep on walking. They can be lethal to other dogs without thinking twice about it. They are usually pretty calm around humans it just other dogs that they have an amnity for. Their owners are usually knuckle heads who don't have a clue as to the power of these dogs jaws. To get a pit bull off another dog you need a large 1 1/4" x16" wooden dowel to pry the dogs jaws open. I would never stick my hands in their mouths to do this. The other option is to carry mace for most dogs but which is usually ineffective with the terriers. Other methods of breaking up a fight are to have to people both grab the two dogs rear feet and start walking backwards while pulling them apart. Putting a chair with legs between them can be effective as a temporary distractor. My approach at 6'2" 220lbs is to concentrate on the fight and then at some lull in the action which there will be... grab the aggressors collar and neck skin firmly and yank that dog out of there and get him at least 10 ft away to break eye contact. Hopefully the other dog owner is trying to control his dog as well. You have to absolutely go into this cool calm and collected knowing that you can and will do this. This is not the time to show fear. You must remain calm at all times. No yelling or hitting the two dogs with a leash. That just excites them more. The other no,no is to pickup a smaller dog in an effort to protect it. That's the best way to have an aggressive dog crawl up your chest and eat your face. You have to protect yourself first and then the dog. Your best offense is a good defense. Before releasing your dog into a new situation monitor the population of dogs especially if your the new dog on the block. Its their turf and not necessarily neutral turf to dogs that come over every day. Any type of pit bull terrier I would stay away from if you value your own dog. As for your dog it will not suffer any long term damage, try to create a controlled situation between known nice dogs to socialize with. In the long run you may find that you won't be able to enjoy your intact dog off leash without some very rigorous obedience training and onsite proofing. When you have hormones coursing through your blood it sometime hard to think of anything else but sex and fighting. Just ask any human teenager! And thats what age these dogs are. The best course of action is to get him neutered if he is not going to be shown, for both of your peace of minds. They are so much easier to work with. Homework reading is The Culture Clash by Jean Donaldson. A great explanation of dog behavior mixing with human society.
Jim LaFrom San Jose, Ca now get out there and work dem workn'dogs