I have the following rules in my listing:
During winter, we will accept pets in the bedroom and house with the following conditions: We will charge a pet cleaning fee depending on the pet size and breed. Please contact us before booking if you plan to bring along your pet. Pet must not exceed 10-15 pounds and must be trained. Pets nails must be trimmed. Only dogs and cats will be accepted as pets. Only one pet per stay will be allowed.
Please understand, my wife loves pets, however; we are not a kennel and we will not be responsible for the pet behavior and/or if the pet causes damages while the pet's owner is away. Any property damage caused by the pet will be the pet owner's responsibility.
If they contact us before booking, I usually send them an offer with the new rate. If they let me know after they book, I send a request for extra money. If they do not let me know and show up with a pet, I will charge them a little more and expect payment in advance, otherwise they will not be allowed to stay and I will contact Airbnb immediately.