Go to the listing and confirm to the guest that the cats are not allowed at the property and they will need to put the cats in a cattery or you will need to ask Airbnb to cancel the booking and they will need to leave the property @Front-Desk6
Obviously message them on Airbnb with proof of the cats being at the property first so there is a record. @Front-Desk6
according to your profile you are a guest rather than a host. which property are you referring to.?