Advice on how to choose your dog trainer
Please be careful when choosing your dog trainer. Don't let them bully you or your dog. There are so many ideologies within the dog training world, that it is easy to get dizzy from all the different advice given!
Make sure to meet your dog trainer and watch one or two of her/his classes or private trainings (providing their client agrees), before you sign up for training with them. You should feel completely comfortable with the methods they use when training dogs. If you feel uneasy or doubtful with their techniques, find another dog trainer!
If your vet has told you your dog has a behaviour problem, please seek a second opinion from a professional dog trainer/behaviourist. Unfortunately vets get our dogs into all kinds of trouble with badly diagnosed problem behaviours. Often it is a case of them pointing your dog out as dominant, when in fact your dog is very scared and only showing agressive signals to protect himself/herself.
A professional dog trainer/behaviourist should be able to assess your dog and read his/her body language and from that be able to tell you WHY your dog behaves the way he/she does and what you can do to fix it.
See a dog trainer or behaviourist sooner, rather than later. Don't let your dogs bad behaviour become a routine, before you seek help.