@James3128 Whenever I accept a guest, I send them an email that repeats the terms of their stay --
"We look forward to your arrival on (day) after 4:00 PM, with a planned departure at 10:00 AM on (day). Your reservation is for X adults, X children and NO PETS."
When they see that their reservation is for NO PETS, they will immediately respond with the details about Fido and are panicked about what they are going to do with Fido if they cannot bring him.
We have a Pet Fee on the listing and mention that in the description, but guests still "miss" telling us about their pets until the email confirmation about their booking.