If you're always jumping because of unexpected fights, growls and doggie arguments, it might be time for an intervention. Just as siblings sharing a home will fight, so will dogs living under the same roof. While the occasional disagreement is not a problem, constant picking on each other will make everybody miserable. The sooner you intervene and help them make peace, the faster peace will return to the home.
Figure out what triggers the problem. Is it always the same dog picking on the other? Does it happen always over the same issue -- such as jealousy over a human -- or random things? Do you have an effect on the problem? For example, some dogs will pick on each other when the owner is around, either as a way to show off or out of jealousy. However, the same dogs might get along just fine when other humans -- but not the owner -- are around. Until you've identified the cause of the problem, you won't be able to solve it.
Spay or neuter both dogs. There's at least a chance that the issue is related to hormones kicking in. If you have two boys, for example, they might suddenly feel the need to establish rank. So when one dog picks up a toy or a bone or goes to sleep in certain areas of the house, the other dog might suddenly feel the need to let him know he can't do it -- just because he doesn't want him to.
Eliminate sources of conflict. Feed the dogs in separate corners of the room, or even in different rooms if necessary. Don't leave nice toys or chew bones lying around the house. If you give them a treat, make sure it's the kind they can finish up within a couple of minutes.
Remain neutral. While it might be tempting to scold the attacking dog and baby the victim, you might just be giving the dogs more reason to keep fighting. A firm "no!" when the bullying starts should be enough. Try a training whistle or even a spray of water to stop the fight, or to prevent it if you see it coming.