I'd start by calling whoever wrote the note to see if they're even a real person and can verify that the tenant has a legitimate health reason to need the Emotional Service Pet, and if so then verify that whoever wrote the note is qualified to write prescriptions (must be an MD, PA, APRN). 

So much about the STR, MTR or LTR approach comes down to your individual goals, possible pain points and preferred investing prescriptions.

You'll either need to acquire/reacquire prescriptive easement rights, negotiate a license or sue to quiet title if an abandoned claim. 

Part of the agent's role is to supervise to be sure that nothing bad happens, or to work to rectify it if it does.Either way, always advise the tenants well in advance (according to the terms of your lease) and tell them to secure all valuables (money, jewelry), prescription and weapons.I also recommend minimizing the intrusion on the tenants by scheduling group showings at specified times only. 

It does not matter if you have a "card" with a prescription...you're not smoking that stuff here, period.No animals or pets.No felonies or evictions, ever.Personal experience tells me that you will waste time posting on Zillow. 95% of the people do not even read the ad.

While you cannot ask WHY they need the animal, you can request proof of prescription.

It was fairly dark, much about our economy being a multi-bubble economy, the weakness in housing for various reasons (including the 50% or so cash transactions and the REITs buying up quite a bit), and inflation scares, our massive debt problem, the impending meltdown of the dollar, politicians being inept, and the prescription of getting out of real estate/bonds/securities and getting into gold and inflation-based securities, etc.

There is a safe harbor (sort of) at 2 years with specific use requirements from the IRS but again the safe harbor is not meant to be prescriptive but only descriptive of one period that would be acceptable.Best advice - say your explanation to the mirror. 

Your listing language is fine, and you aren't doing any of the stupid things many landlords do, like use very prescriptive language or listing lots of rules. 

(At least in my market) You are in a more red leaning state which may have case law that is more landlord friendlyIf the dog is an Emotional Support Animal you can request a doctors note, or a prescription for the dog.