Tips for dealing with a growling or biting dog:
Consider contacting a Veterinary Behavioral Specialist for a consultation.
When searching for a trainer, make sure you find one that is experienced with aggression and is planning to use positive methods to help your dog learn that what he is upset about is actually okay.
Avoid using "corrections" or punishments. Instead, teach your dog to have positive associations with the things that currently upset upset him, using baby steps. Here is an article on working with your aggressive dog.
Most importantly, do your best to prevent provoking the aggression and keep everyone safe!
The products below will help you to train your dog to be less aggressive.