Our Mobil groomer requires shots to be up to date. Mainly due to rabies. Her insurance requires it. Also, bordatella protects other animals because it can be spread in confines spaces. Sounds like you are dealing with Petco.
Not Petco.
Also, I don't have any objection to requiring that shots be up to date. I fully understand the reason for that, especially Parvo since that can be spread so easily. My objection was tying in to COVID-19.
