It is quite simple:
The horse as a sentient being.
The client as an equal team member, along with the Mental Health Professional and the Equine Behavioral Specialist.
All of whom in a square - each one taking responsbility for himself.
That is the essence of the Quadrant approach.
The horse is not a therapist, tool or attachment substitute.
The client is not broken, damaged or less.
Neither one in the team is taking responsibility for the other - and all of them are working together to assist the person asking for help.