My puppy's hair is thinning on her head, and I see scalp. Is it bad?

It is possible that your puppy is having a little bit of hair thinning, but it's not something that you have to address right away. Especially if it's barely noticeable. The reason I say this is because puppies are highly susceptible to overpopulation of Demodexx mites, which can cause localized or generalized hair loss with secondary infections. However if the hair loss remains in one area (localized) there is a chance Penelope can resolve this on her own as her immune system develops.

Keep an eye on things for now to see how things develop, and if the hair loss worsens and forms actual patches of alopecia then it's time to see a vet at that point for skin testing and proper treatment. Also even though you don't see fleas it doesn't mean that they are not there lurking beneath the hair. They can be very inconspicuous, so it's best just to keep Penelope on monthly flea prevention, even if she just goes outside to potty. Because it's a fact that 40% of indoor dogs still get fleas, and that can lead to itching and thinning of hair also.