It started out as good fun, but suddenly there are flashing fangs and earsplitting growls. Your dogs are fighting over who-knows-what. (Maybe a bone, toy or offense?) Dog fights can sound frightening, but most of the time the noise is more for show than anything. Dog fights are usually short (but not so sweet) and end with one dog backing down and no serious injuries. Sometimes, however, a fight can drag on or one dog can get hurt. As the alpha of your little pack, it is up to you to play the peacemaker and stop or prevent fights from happening.
Observe your dogs' body language to see if they are actually fighting, or if this is a friendly wrestling match. Dogs use their teeth (and their growls) to play with each other, and even a game can seem quite violent to a human observer. Are your dogs rigid and stiff, or are they bouncing around, tails wagging? If it's the second, this is probably just a game.
Break up fights by interrupting them. Clap or shout to get your dogs' attention. If this isn't enough, try water, or throw a blanket over the top of the dogs. Don't physically separate the dogs unless you have to. Never grab your dogs' collars during a fight, or they may reflexively bite you. Don't try to separate them alone either. Get someone to help. Grab each dog by the hind legs, at the very top of the leg (near the hips) as close to the body as you can get and slowly walk them backward at the same time. Don't grab their lower legs or you can injure the dogs.
Feed your dogs in separate rooms in your house. This will stop them from competing over food. Don't leave coveted items such as bones or toys on the floor unless you are able to supervise. Watch for situations that might cause fights. For example, if there is only one bone on the floor, you may have problems. Eliminate possessive fighting by controlling your dogs' access to these items.
Interrupt your dog's wrestling matches if you feel they are getting too heated and may turn into a full-on fight. Try teaching a command such as "gentle" to warn your dogs to back off when they play too loudly or too rough. Start with a loud noise such as clap as you say "gentle" to get your dogs' attention. Reward them for easing up or let them continue playing at an appropriate level. Each time they get too rough, interrupt the game. Separate them in separate rooms for a few moments if they refuse to calm the game down.
Train each dog with basic obedience commands. This can help you have greater control of them when they get too excited or agitated with each other. Always reward calm behavior. For example, rather than risk fights by letting them trample each other in their rush to get outside, require them to sit and wait at the door until you release them. Reward them for doing so. Likewise, give them privileges, such as chewing on bones, only when they are calm. If they start to get aggressive with each other, remove the bones (and the temptation).