We have a Springer Spaniel who appears to be developing a fairly bad case of springer rage syndrome. I understand I should talk to a veterinary behaviorist about this. Please advise.

Thank you for your question.  It sounds like you understand that aggression of any type or reason is unacceptable and that you need to seek help for your pet.  A professional dog behaviorist is a great place to start.  There are a wide range of educational levels and fees for these professionals.  We recommend these two individuals:  http://baysidebehavior.com/contact/index.asp and www.drjddvm.com