What do you do about two dogs that growl and bite each other?

I have a seven year old lab and a nine year old jack russell that have been raised together and all the sudden the growl and bite each other. The jack russell starts it and the lab is so much bigger that of course he ends up hurting the jack russsell. The fights are about nothing obvious they walk by each other and growl then the jack attacks. I have been bitten today twice and this can't go on. What would make them like this. What should be done. How should I break them up with out getting hurt?

Are the dogs males or females are both? Are the spayed/neutered? There could be tons of things that could cause your dogs to bite and fight one another, and if they are biting you they are horrific pets and are Poorly trained. You need a dog behaviorist ASAP...

If your dogs do this at home, keep containers of water in your garden/yard. If your JR growls throw water on his head. If you fail to do this in time and they start to fight in the garden/yard, throw water on their heads. If they start to fight in the house use a starting pistol, the noise will distract them and they will stop fighting. When they stop don't separate them, walk tall and growl as you walk away and ignore them. You won't get bitten if you do this and your dogs will respect you.I am assuming that some of the answerer's will tell you to have both of your dogs castrated if they are both male. Please don't do this, as you will put them back on the same level again and this will not help. Have the more submissive dog castrated and leave the "top dog" intact. You must then favour the top dog, feed him first, put his lead on first and when you are in a safe area take his lead off first. Let him into the car first etc.,Never ever give anything to a dog if he does not earn it. If you want to give them a treat, make it sit or do something before it gets a treat. If either of the dogs approaches you for a cuddle, get it to do something before you cuddle it and don't let either of them on the furniture.The less dominant dog will then have a stress free life and I suspect that this is the lab. There are lots of mercenary vets, those who are will tell you to get both dogs castrated. Some vets will suggest anything for additional income.