To shadow a Board Certified Veterinary Behaviorist. They commonly treat: 

Aggression    
Cognitive Dysfunction (Dementia)    
Leash Reactivity
Noise Phobia
Thunderstorm Phobia
Urine Marking
Separation Anxiety  
Refractory Housetraining 
Urination and Defecation outside of the litterbox                  
Feather damaging behavior
Compulsive behavior
Night Anxiety
Generalized Anxiety
Global Fears
Fly Snapping
Circling/Spinning