If you take a look at Phil's Instagram, he has a history of going to pet stores that spans years. This is one of his hobbies. He likes to look at animals.
If we are to believe she transferred jobs from Michigan, are animal shelters able to do that? I dont have any idea. I assumed they were typically run by the city government or some non profit organizations.
I also did a quick search and didn't find any 24 hour animal shelters in his area. Most close well before 11pm, when Kat allegedly gets off work.
I would also speculate that Kat doesn't work at a pet store, like Petsmart for example. The majority of people who work at pet stores are also pet owners. It's kind of like how people who work at Gamestop play video games. If Kat transferred from a pet store, it would be likely she would own a pet and as has been stated, Kat loves cats. Watching Kat's YouTube streams, there is no cat in the footage. I am drawing the conclusion that if Kat worked at a pet store, she would have a pet. If Kat had a pet, she prefers cats and would have a cat. Cats like to prowl around and interact with their owner and no cat was seen doing this. So I conclude Kat did not own a cat and probably didn't work at a pet store.
While this might just be autistic grasping at straws, I do not believe Kat works in a pet related job. The whole pet theory really boils down to Phil likes to go to pet stores and animal shelters and not buy anything.