Should I fire my veterinary team bullies?

A Firstline reader asks for help to handle two team members who bully the boss and their co-workers and refuse to work with other members of the team. The question:

"I am being bullied by two of my employees. They ignore requests and directives from the veterinarians and office manager. They are rude, unhelpful and sometimes mean to our clients. They refuse to work with certain staff members, including veterinarians, and refuse to assist with certain clients that they have decided they do not like. On multiple occasions, I or my practice manager have explained our goals, policies and expected performance to them and they argue about why they are justified in their actions. I have been a practice owner and employer for almost 30 years and have never experienced such shenanigans from my staff. What happened here? Should I cut back their hours and hope they quit or just dismiss them and get it over with?"