In Home Aggression

Question
I have a two year old female Airedale Terrier and a six year old male miniature
Schnauzer.  The Airedale has been with the schnauzer since she was about 6
months.  They have gotten along great for the past two years until recently.  
The airedale has started to become aggressive with the schnauzer and has
attacked her on multiple occasions to the point of needing medical attention.  
The attacks seem to be unprovoked and have never occurred when I am
around only when my children or wife have been present.  The airedale
accepts me as dominant.  I am not sure if this is her now trying to assert her
dominance or what.  She starts by posturing and then will grab the schnauzer
by the back of the neck and shake him violently until being pried off.  I am at
a loss as to what to do and fear she will kill the smaller dog one day.

Answer
This is a serious problem, not only because the smaller dog is living in absolute terror but because this appears to be related to your not being present.  I suggest you separate these dogs immediately; you need to obtain the in person evaluation and help of a certified applied animal behaviorist.  The Airedale is an extremely tough breed of dog in terms of obstinacy, rank opportunistic dominance and its related aggression.  Her posturing is a clear signal to the Schnauzer of her intentions and there must be a failure of communication between them, or the Airedale is simply not behaving in a cognitively correct manner.  If the latter is the case, you must give immediate attention to this problem in order to safeguard your children.  A professional will be able to evaluate the communication, or lack thereof, between the two dogs, determine temperament in the Airedale, and ascertain from an in depth interview of all family members whether or not this is a rank opportunistic problem.  You can call the veterinary college in your geographical area and ask for referral, or you can try this site which I discovered on the internet.  They apparently do check educational and professional credentials and offer referral both abroad and in the US:
http://www.iaabc.org/