Dogs fighting

Question
Hi. I have two lab mixes, both female and both spayed.
The older female Was about 5 when we got the 6 week old other female, she took her under her wing and cleaned her and played with her, toaught her how to play fight etc ...
Well, the younger dog is now almost 2 years old and suddenly they have been getting into some nasty fights.

I realize that they are fighting for dominance and wonder why when the younger one had always let the older one have the dominance before.
I currently have them seperated and I am not sure if that is good or bad?
I am terrified of another fight and someone getting hurt.
I have read about how to break them up safely but these are also big dogs weighing about 85 - 95 lbs each.

I cannot bare to get rid of either of them, I love them both.
       I am trying to establish being pack leader.
Is it right to muzzle one when it starts to growl at the other?  Also, what is your opinion on the new stun batons for dogs tom only use if you cannot get them apart?
Will these dogs ever get along again. my heart is truly breaking over this.  Thanks, Rose

Answer
Dogs are not mature until they are 3 years old.  As a dog matures, it is common for them to challenge others for pack rank.  The younger one has decided to challenge the older one now.  The key to most behavior problems is approaching things using the dog's natural instincts. Dogs see all the people and dogs in the household as a pack with each having their own rank in the pack and a top dog. Life is much easier if the 2 legged pack members outrank the 4 legged ones. You can learn to play the role of top dog by reading some books or going to a good obedience class. A good obedience class or book is about you being top dog, not about rewarding standard commands with a treat. Start at http://www.dogsbestfriend.com/ For more on being top dog, see http://www.dogbreedinfo.com./topdogrules.htm

Even better leadership on your part may not be enough.  A private trainer or behaviorist might or might not be able to help.  2 females is the combination most likely to cause insoluble problems.  In some cases, even the most experienced dog owners can't maintain peace.