Support animals with no pet policy

[Glenn Finniss]

I have a strict no pet policy for my units.  I used to allow small pets but a couple irresponsible tenants allowed there animals to damage carpets, walls, etc. so I got out of the pet business.  Recently, a tenant moved a cat in without my knowledge, claiming it is a support animal and is in the process of getting the paperwork to back that up. I was alerted to the cat by another tenant who I refused to let bring his pet.  How would you handle this situation?