My father has dementia. Is he starting to hallucinate?

He’s never had hallucinations before. He lives in our guest house. He said the other night a pack rat woke him up because it bit him on the finger, and it hurt pretty bad. We live in the desert so it’s possible I guess one could have gotten in the home, but I find it strange it didn’t leave a bite mark on his finger. Don’t they have pretty large teeth? So I guess all I can do is call an exterminator to have them look around. My father tells me last night he had a dream that kittens were in his home and sleeping on top of him. I’m wondering if he’s dreaming of rats and kittens or hallucinating or what? Do hallucinations usually come on at night? (He has vascular dementia. Perhaps the stage before not being able to bathe or dress yourself). Thanks for your help.