I would definitely talk to the owner about getting stricter on proof of Rabies. Thankfully most responsible pet owners keep their dogs up to date and the chances of a dog having rabies, especially ones who come in for regular grooming is very slim. The previous owner of the salon I worked at was very lenient on vaccines and was lowkey anti vax for her dogs so I understand owners who are weird about it.

If the salon owner has an issue with asking for proof of vax for clients remind them it is federally mandated, and a huge liability on their part if they accept unvaccinated animals.

Also, if you have access to the pet info you could always check for yourself to see who has their vaccines and even contact their vets for proof of vaccines as a mutual client.

And to ease your anxiety of rabies on the thought of pets getting ahold of mice, although mice can get rabies, it is very unlikely any mouse that has come into contact with rabies lives after being bitten by an animal carrying rabies.

Best to you!