Breaking a dog fight is stressful. A break stick is used to part a dogs jaws if you can not get them to let go by standard methods. Before Grip If the dogs don't have a grasp yet, you may be able to break the fight using other methods. Jerking the dogs back by their collars, a loud and firm break command, banging pans together, a bucket of cold water, a water hose, or placing a barrier such as a baby gate between the two dogs may be enough to stop them.
Be safe: don't put your hands anywhere near the mouth of the dogs.
If one of the dogs has a hold, a break stick should be used. It is much easier to break up a fight if you have two people, but you can do it by yourself if you have no other option. If both dogs are fighting and you are alone, you may need to restrain one of them by tying one dog to something solid. When one of the dogs is tied, you must "break" the one that is not tied first and immediately pull him/her off. If both dogs have a hold, you will then have to break the second dog also.
Stay Calm. I know it's easier said then done, but you need to keep your mind straight.
Approach the dogs, straddle one with a grasp, and then wrap your legs around the dog's hips right in front of the hindquarters. Make sure your legs are securely wrapped around the dog. With your break stick in one hand, hold your dog's collar firmly and pull upward slightly with your free hand. (This is a good reason to always maintain collars on your dogs).
Insert your breaking stick behind the molars where there is a gap. If the space is small, you may need to work the stick in somewhat. The stick should be put into the dog's mouth between 1/2 and 1 1/2 inches.
Turn the stick in the same way you would a motorcycle throttle. This causes the dog to re-adjust its grasp and bite onto the stick, releasing the other dog. If both dogs have a grasp on, you'll have to separate the second dog from the first.