I notice that also here we have another example of a Susanoo wielding a Yata Mirror.
He also seems to have the other two Three Sacred Treasures as well.
What makes you think she spent a bunch of time as that cat?
In fact, earlier she showed up in the form of a completely DIFFERENT cat.
No, she said "He owned a few cats, so I transformed into one and snuck out." implying that the cats gave her something she could blend in with.
Now that she's in the woods it would make more sense to become a squirrel or bird or something.