@Garrett53 I'm sorry, I reread your listing and now do see that you mention the cat. However, I'm normally a pretty thorough reader, which many guests aren't, so I think you might do well to make it more prominent. Lots of guests don't even bother reading the listing info, they just look at the photos and price and book.
The first mention of the cat is under "Backyard" where the last line is "please don't let the cat out", and the other mention is under "other things to acknowledge", but only seen if the guest clicks on "read more" under house rules. And since Airbnb buries our house rules at the very bottom of the page, where many guests don't even bother to scroll down to, I still think you might mention it more prominently- just add a photo of the cat, with the caption "my co-host" to the photo gallery, which almost all guests look at.
Oh, now I just see your latest post where you say you also make mention in your booking message to guests. Okay, this girl is a real loser if none of that registered with her. Looks like she didn't read the listing info, the reviews, or your message.
I mention my dog and cat and in capital letters, say "PLEASe DO NOT BOOK IF YOU HAVE ALLERGIES TO DOGS OR CATS.
I do agree that this guest has to go, though. It's so entitled to expect you to remove your pet from your home, her attitude alone would make me want her gone. And if I was highly allergic to something, I'd be sure to take responsibility for my own health and check with the host that the allergen wasn't present before I booked a place.