
The vet could be on to something. If she feels unsure of her place, but you are reinforcing the fact that you think she is top dog (feeding her first etc.) then it could be forcing her to try & show him who the boss is?? I think that
confusion over hierarchy is the biggest cause of problems, as generally the 'top dog' does not need to resort to violence and a follower will not challenge a top dog, but when the positions are not clear, they need to try & figure out whos who.
We have a dominant male lab cross (14 yrs old), when we got our pup we treated the old boy as top dog (feeding/fussing first etc..) believing this would stop any problems. We started to see that the old dog was being a bit of a bully, nothing aggressive, just if anyone was fussing the pup then the old dog would push himself inbetween, he would also push the pup out of the way to go through doors first, things like that. We started to treat the pup as top dog and things have changed. The old dog will step back to let the pup go through door first, if the pup is being fussed and the old dog does come over, he will wait patiently to share in the fussing. If they were both being givven a treat at the same time, they would both snatch, now they wait patiently.
I am a believer in the pack theories (dog pack, not wolf pack). I also think Cesar Millin is brilliant, he says that dogs communicate though body language & energy. I thought the energy bit was maybee to wierd, but givving it thought I do believe it. Think of the saying 'could cut the air with a knife' refering to the atmosphere between people. We can all 'feel' the sadness, happyness, confidence of other people it make sense that a dog can do this too. In fact as they don't rely on verbal communication, they are bound to be better than us at feeling this type of 'energy'.
My pup is very laid back. When he has met dogs at he vets he sits calmly, with no unfiendly/fearful/exited/dominant body language whatsoever, yet, most dogs will have a go at him :( He doesn't react whatso ever. The other dogs must be reacting to something, I think they get confused, they can tell he is a puppy (even though he is huge), but he gives of an aura of being self assured, sort of 'I'm the man' in a calm, non cocky type of way, very hard to explain.
Anyway, enough of my rambling on, I'm sure most people will totally disagree with me, but this is just my view on things :)
A behaviourist would definately be the way forward. It's easy for all of us who can't see exactly whats going on to give advice/suggestions, but a good behaviorist will be able to see the problems for himself & know the best way to sort it oot. Do your vets reccomend any behaviourists?