To be accurate, that’s only stipulated in advertising. When it comes to a tenancy agreement, typically you have a clause that states that the LL should not “unreasonably deny” a request for a T to have a pet. Tracy has just posted an example of a situation that would be a reasonable way to deny that request: the pet caused damage.
But if a T said their son wanted a small lizard in a tank in his bedroom, a LL would be hard pushed to find a reasonable way to deny that request.
For me, denying a request that is reasonable simply sours the relationship with the T and marks the beginning of the end. It’s my property but it’s their home and I need to bear that in mind whenever I get a request.
I sympathies with your situation but, I’m afraid you’ll be disappointed since the DPS / Courts will apply a wear & tear percentage related to the period of occupation irrespective of pet damage.
I had a judge dismiss my claim for nicotine staining / cleaning and fumigation stating the decoration was covered by the W&T allowance for the period in occupation of that tenant. It took a fair bit more than a simple fresh coat of paint to rectify their abuse.
At least you get to avoid maintenance issues. I’m very allergic to cats so would have the same attitude.