sudden aggression issue with my 2 aussies

Question
I have 3 dogs in my house - 2 male aussies (nuetered) and 1 female toller (spayed).  I have had the aussies since they were puppies, they are now 3 and 2 years old.  The toller we got at 8 months old - she is now 2 years old.  All 3 dogs have always gotten along and played together.They were all kept together during the day in a large room together and had free reign of the house when we were home.  In the past week the 2 male aussies have started fighting suddenly - it seems to be over attention (food and toys were not invovled).  Neither dog has been injured - but we have had to physcially seperate them.  Right now we are keeping them completely seperate from each other.  Both of them are trained dogs - I have done agility and obedience training with them since they were puppies, one has a CD title.  I have an appt with a trainer next week to see if she can assist us - but I am looking for any ideas or help I can get on what I can do to get them not wanting to attack each other.  Thanks.

Answer
Be careful of the trainer; be absolutely certain she knows what she's doing.  DO NOT use coercion or any method of discipline or punishment, it will make matters seriously worse and not able to be rehabilitated.

Something you didn't see touched off this sudden problem (given the dogs' heavy socialization to other dogs vis a vis their obedience titles, requiring many hours of work).  You must establish, by observation, who is dominant IN FACT, not in appearance.  This requires you observing both dogs' behaviors quite closely, both apart and together.  Learn something about calming signals (how dogs communicate with one another) by reading Turid Rugaas' book on the topic and going to her site:
http://www.canis.no/rugaas/index.php

Have someone accompany you with both dogs on leash outdoors in a neutral place.  Approach one another from a distance (a block or two) and closely observe the dogs as they spy one another and begin to get closer.  At the FIRST SIGN of any aggression or fear (hackles raised, direct staring, lowered head, growling) turn BOTH DOGS around in opposite direction, stop, make dog(s) "sit" on command, go back toward one another.  Do this until there is NO SIGN of aggression/fear and then walk the dogs parallel with one another (not too closely, but casually) and observe their interaction very closely.  Watch eye movement, body movement, tail set, ear set.  Stop with both dogs and see what they do: does one turn his back on the other?  Does one turn his head away or avert his gaze from the other?  Is one lip licking or yawning? etc. What you're doing is attempting to establish who is the naturally dominant one (I think they must be close in temperament and that is contributing heavily to the problem.)  REPEAT this exercise daily for at least 30 minutes for one week and take notes.  You should be able to establish who is the most dominant and then proceed, indoors, to promote that dog over the other and use a CLICKER (ClickerTraining.com) to signal to the subdominant dog that HIS subdominant acceptance is being REWARDED.  If you can get someone to videotape this FIRST session outdoors with the two dogs, do that and (if you can) upload it into a PRIVATE followup posting here and I will look at it.

Put BOTH DOGS on NILIF (Nothing In Life Is Free) right now; if you are able to repeat the above exercise daily for a week, you SHOULD have significantly lowered the fight-on-sight problem indoors.  In order for you to be able to promote the appropriate dog and demote the other, they must be able to spend time indoors together BUT ONLY when you are present and ONLY with both dogs on strong, nylon house tab (leash).  FIRST you must prime them by your outdoor exercises.  THEN you must demote both dogs with NILIF and learn about using a clicker (if you don't already know how).  You will be clicking the subdominant dog for offering appropriate (and subtle) body language toward the more dominant dog and rewarding them BOTH, this can be tricky and you need to know what you're doing.  

IF THE DOG TRAINER you hired does NOT KNOW THESE THINGS and cannot instruct you on how to change these dogs' minds about one another, GET RID OF HER and find a certified applied animal behaviorist.