food aggression

Question
HI,

I have 2 10 months old labs, I have had labs all my life.
the current ones are brothers, buddy, yellow and bear ,
chocolate.  I have been to sooo many trainers with my past
labs, I have been training these guys alone since I had them
at 8 wks, never a problem , very loving, training has gone
well.  They have been really loveable dogs...........until
recently.  Bear, my chocolate has an aggressive side and I
hate it, usually with food, the other night he had a bone
and my daughter bent down to pet him and he went nuts,
nipping at her, growling, I hate to say it but I think he
would have bit her if she didn't pull her hand back.   
around the same time he was sitting in my spot, so i went to
nudge him over and the same thing,  I of course took control
of the situation and moved him.   we have been going to the
off lease dog park since i got them, never a problem and
again around the same time a puppy came up to my boys and
bear went nuts.   again i was able to get him under control
but i fear when I am not around or if it is my little niece
and I can't stop it.  I am sure you are going to say
training is needed but what I don't understand is why the
sudden behavior.   I have never ever had a lab show
aggression like this, I honestly didn't think it was in
them.  Thanks for your help

Answer
Ten months is about the age that dogs start testing their humans again. Having two boys together can be a handful when the hormones start flowing, which is just that same age as well.  I would take a step back and forget that you have obedience trained the dogs successfully and just think that this is a time that you are going to have to go over everything again and reinforce all the commands with extra vigilance.  

A behaviorist vs. a trainer would probably be more beneficial as you need someone to observe the behavior between the dogs and the interaction with the people in the house.  

Is it possible the other dog gets in the way when the aggressive one wants to eat?  Have you looked into the training method called "nothing in life is free"? You can think about feeding your aggressive dog by hand so that it knows that all food comes from you and belongs from you.  You may want to consider feeding the dogs apart while in the same room (opposite sides) or in their crates.  

If a dog has a dominant personality, it doesn't matter if it's a lab, it can learn to be aggressive if it thinks that it's in charge of the home and YOU aren't doing what it wants.  But the key is to try to understand the underlying reasons for the aggression.  Something's happened, very possibly inadvertently and not obvious to you.  Look for stressors.

I unfortunately haven't had food aggressive dogs myself.  We have quite a few labs including two 2 1/2 year old intact littermate boys, and they were raised knowing that we own the food, they don't go to other dogs bowls, and the first time I saw someone get snarky over a bone with the other, the treat was removed and they were corrected.  But you have to be 100% vigilant with them.  

This seemed like a good article:
http://www.dogproblemsolutions.com/how_stop_dog_food_aggression.php