Your options:

1.) Get your pet registered as a companion animal, thus making it illegal for the landlord to charge you extra rent. (Bonus: You can basically live anywhere with your animal if you do this, even at "no pets allowed" places)

2.) Rent elsewhere. No one is forcing you to live at a place that charges $100 extra a month for pets. Find a place that doesn't or has pet rent for less. Can't find anything where you want to live? Look further out. Then you can write another I, Anonymous post complaining about gentrification or how so many people move here that it forces the rental market up.

Oh I, Anon - you clearly have never moved in to an apartment after someone lived there that had pets. They are disgusting and they smell like sh*t. There's a reason places charge so much for people moving in with pets...it's for the clean up they have to deal with. So you can deal with the extra expense and stop complaining about life, or go elsewhere that doesn't charge as much. Don't be lazy...do your research for cheaper apartments.

Or... The landlord/management company has previously had to replace all the carpet, every window covering, and repaint the entire interior of said house when tenants with "one cat" turned out to have a whole lot more-- plus a dog-- all with poor house training...

When one "bad" tenant costs thousands of dollars more than the security deposit covers you very quickly switch to 'no pets' or higher deposits and monthly fees to protect your investment. Sadly, policy has to be geared to protect against the worst renters, not the best.