Glad I read the whole thread first :)Your first line of defense when getting these requests is simple: if the nature of the disability or need for the animal is not obvious (i.e. a "seeing eye dog" for a blind tenant), you are legally permitted to require the applicant provide official documentation of the need for the animal, and the type of animal, from a physician, psychiatrist, social worker, or mental health professional.

I'm a physician, and there are several banks that offer personal, unsecured lines of credit specifically for physicians. 

Occasionally we have applicants with service pets with a not from a physician.

(Once a physician, once a counselor) Our lawyer sent the care giver a certified letter and a call informing them that any liability from a lawsuit resulting in an injury from a vicious breed animal they approved as a service animal would mean we in turn would be including them as liable on the given suit, and to please forward us a copy of their liability limits..In both instances letters were immediately withdrawn..

I will be a physician in 5 years (just beginning residency) and am brand new to the REI world, so this question is important for me down the road.

Most of our homeowners are professionals - physicians, attorneys, etc., - many of whom have never even seen their rental in person. 

Do you call the physician?  

I am negotiating a lease with a physician for my medical office building.

Easy to hire or restart once you’re in practice.Continue staying up with literature and consider buying with Physician loan if rates are low when starting residency rather than renting for 3-5 years.

That's better than nearly all physicians make.