Late last year, one of my tenants contacted me with the inquiry about adopting a dog. We have leases with no pet policy (which they signed). Since they always pay on time and are great tenants, I told them that yes, that I would be happy to change the clause for them as an exception as they were such a great tenants.
I also mentioned that the building has a pet policy (condo board) which states that if the dog becomes a problem, it would have to go and that fines could be made. (They agreed)
While my general policy is not to allow pets, I am actually thinking that if such clause is removed then a would capture a bigger share of the market as there is a lot of people with pets. They have difficult time getting into units due the no-pet policy.