(pet stains that ruined a good portion of the subfloor throughout the house), needless to say it was quite the job for my father and I to work on and update the house over a 3 month period.

Repair negotiations, certain details to add to the lease, pet addendums to the lease, etc.

I don’t want to poison tenants pets, but after talking to the manufacturer, it seems like this isn’t a risk, hardly at all.

Lots of pets.

Think of all the things that could go wrong and see if the lease addresses them: unauthorized pets or tenants, early termination, security deposit, lease violations, late rent, eviction, lawn maintenance, parking, etc.5.

I don't have advice but I personally might replace the floor and take a certain amount of money as a refundable pet deposit that you will give back on move out if the floor is in good shape.

There's a difference between vandalism and negligence; the latter is not usually criminally actionable when it comes to non-animated property (i.e. a car or a house versus a little kid or a pet). 

Anyone have experience with an irresponsible pet owner tenant? 

The lease and other documents provided by the former PM clearly stated that there were no dogs in the household and that pets would only be allowed after a pet addendum was signed.

If she claims one is an ESA so she technically only has one pet, then you can tell her that the pet requires a $500 non-refundable deposit and an extra $100 a month for the pet.