@Kelly-and-Ronda0, If the guest is simply inquiring, you do not need to pre-approve or decline. You only need to respond to maintain your response rate.
If the guest is requesting to book then I would ask them to cancel their own request since pets are not allow. OR you could accept them and tell them you would be happy to host them without their pet and under no circumstances is the pet allowed in the house. If they would still rather bring their pet they can cancel within the next 48 hours for a full refund and book another Airbnb, which allows animals.