It's hard to say with pets. I know my dog didn't like it back when he could hear. He'd hear it from two rooms away and come running to bark at it. I would have to shut a door to keep him happy.
Info on Google is mixed. Some audiologist don't think it has negative effects, but some manufacturers of industrial cleaners say to use protection.
I simply put on a pair of muffs, since I've experienced how loud it actually is. What hearing I have, I want to keep.
Regardless, it's a great tool, and one that everyone serious about vinyl should get. But like most powerful tools, use with care.