@Nancy1248
I agree with @Lori2546 and @Helen3 that no refund is due if it was already stated on your listing that you have a cat. It's the guest's fault for booking a listing that was not suitable for them.
I had a guest leave early once and ask for a refund because she was a light sleeper and due to traffic noise. I said no because this is clearly stated on the listing.
As so many guests do not read the full listing or just skim and miss things, I now ask all guests to confirm they have read the full version, including the house rules. I have added a question in the house rules that they need to answer. I also message them to double check they have understood some key points, e.g. that I have cats, that this particular room faces the road and there is traffic noise or that that particular room is at the top of the house so there are a lot of stairs.
It's a bit of a pain to have to do this, but I think it pays off, as I rarely get guests now who complain about these things.