@Catherine2479 When we decided to accept pets we just raised the overall nightly rental rate to cover the extra cleaning.
Basically average how many nights a year you will host a pet. (Ex. 60 Nights)
Then multiply by your pet fee (ex.60 nights x $15 pet fee= $900)
Then divide that by the average number of nights you get booked in a year($900 / 292 nights per year)
Then increase your nightly rate to cover the additional cost ($3.08 per night)
Everyone pays with or without a pet, you do not need to worry about what type of pet it is and do not have to collect fees that annoy guests or take up time dealing with Airbnb.
Just an idea for you. Hope it helps.
Jorge