The best way of dealing with a dogfight is to keep it from happening at all. If your dog is leashed and shows signs of aggression toward another dog (growling, raised hackles, a stiffly wagging tail), pull hard on the leash, say “no” in a firm, low voice, and move on quickly. When your dog is off leash outdoors, monitor its activities and leash it at the first sign of trouble.
Once a fight has started, direct intervention is dangerous. Try instead to distract the dogs long enough so that they can be separated. Dowsing the fighters with water, throwing a blanket over them, or creating a loud, clanging noise may do the trick.
If the dogs are of manageable size, or if one of them seems endangered, two people working together may be able to break up the fight, but they risk being bitten.
Each person should seize his dog’s hind legs or tail, pull hard and heave the dog behind him. Restraining only one dog can result in injury to both dog and human.
If none of these tactics is possible, you may have to let the fight run its course, despite the risk of serious injury to one or both dogs. When one of them submits by rolling over and exposing its abdomen, the fight is usually over.