@Bryan154 it is not showing separately like cleaning fee, or host fee, it is added on the nightly price. If, for example, your nightly price is 50€ and your pet fee is 10€ then if the guest books 1 night it will be 60 x 1. If he books 10 nights then it will be 51€ x 10 nights (50x10+10=510€ )
Note that pet fee is not possible to set per night or per pet and it is the same regardless of how many pets the guest has and how long he stays.