As the owner of 4 dogs and a cat, I have the utmost faith in my veterinarian to supervise and be aware of the procedures done by trainees and students working at her clinic.  People drawn to such work are a real value to society and the care of our pets.  Most are as devoted to animals as their owners are.  Students and trainees have to learn with hands on applications of procedures and nothing about requiring written owner consent will change the procedure or outcome.  It will only serve to make some owners irrationally afraid of their veterinary care and distrustful of the staff in place.  A veterinarian is the responsible person to supervise and train their staff, volunteers and students.  This change is not needed.