When I was in the acute care world we had a service animal policy separate from the pet therapy policy.  I don't have access to these policies now or I would definitely share.  

There was one point on the service animal policy that we had to reference fairly often involving requests for volunteers to walk service animals for bathroom breaks.  The policy was clear that no staff member or volunteer could provide care of any kind to a service animal - the patient was responsible anything relating to care of the animal.