I've volunteered for a dog rescue for over a decade which uses a behaviorist, particularly for highly anxious dogs and biters. The meds alone are not a magic bullet, and it may take some time to find the right dosage and mix of medications. Behaviorists will usually provide a behavioral plan. In my experience, many owners don't follow through on the behavioral change/modification guidelines. It can take months to change deep-seated behaviors. Follow-through and CONSISTENCY on the part of the owner are key. That being said, I have seen many success stories where owners have been able to manage or improve the behavior of anxious and reactive dogs. But it is not quick nor easy.