LABS GONE WILD

Question
WE HAVE A BLACK LAB WHO IS 7 YEARS OLD.WE HAVE A YELLOW LAB WHO IS 18 MONTHS OLD.UP UNTIL 3 DAYS AGO THEY GOT ALONG JUST FINE.NOW ALL THEY WANT TO DO IS KILL ONE ANOTHER.YESTERDAY THE YELLOW NEARLY KILLED THE BLACK ONE. LOTS OF WOUNDS TO THE BLACK LAB DUE TO THE YELLOW LAB. DON'T HAVE A CLUE AS TO WHAT SETS THEM OFF. THERE IS NO BONES,RAWHIDES OR TOYS THAT THEY ARE FIGHTING FOR.THEY ARE TOTALLY SPOILED BEYOND BELIEF SO FAVORING ONE OVER THE OTHER ISNOT A ISSUE.THEY ARE INSIDE PETS.LIKE I SAID, THEY GOT ALONG GREAT FROM DAY ONE WHEN THE YELLOW PUP WAS BROUGHT HOME AT 8 WEEKS OF AGE.THEY ARENOT NEUTERED.ALOT OF PEOPLE SAY WE SHOULD GET THE YOUNGER ONE FIXED????GOING TO CALL THE VET FIRST THING IN THE MORNING TO SEE ABOUT GETTING CASTRATION DONE ASAP!!!THEY ARE BOTH MALES.VERY GENTLE DOGS UP UNTIL NOW.DO YOU THINK CASTRATION WILL STOP THE AGGRESSIVENESS? AND DO YOU THINK BOTH SHOULD BE CASTRATED??PLEASE HELP AS I DONOT WANT TO GET RID OF EITHER ONE OF THEM..WE HAVE THEM SEPERATED AT THIS TIME BUT AS SOON AS THEY GET A GLANCE AT EACH OTHER, ALL HELL BREAKS LOOSE..THANK YOU..

Answer
Having a good pack structure reduces such problems.  The 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

I think what is happening is that the younger one is maturing and deciding to challenge the older one for status.  Eye contact is one way of challenging another dog.  You can make very effective use of it.  If a dog refuses your command, just lock eyes with it and silently wait.  Much more effective than repeating the command.  

This sounds like 2 dogs each with a high drive for dominance.  To have any hope of restoring order, you must go ahead and castrate the younger.  Stronger leadership on your part will help too.  You may have to castrate the older one too.  Some dogs get along fine, and some never do no matter what.