Mouse fur thinning

Question
My pet mouse Rosemary's fur is thinning on her face and shoulders and underbelly, though she is acting normal, with no extra itching or anything. It's not falling out in chunks. It's just thinning evenly. If she was old I wouldn't be worried, but we've only had her a little less than 5 months.  

Answer
Hi Sierra,

Hmm.  The first thing that comes to mind is the possibility of nervous grooming from stress - does she live alone?  Female mice usually prefer to live in small groups of two or more, and can become stressed if kept alone, causing weird behaviors to pop up like over-grooming.  Another possibility is her diet - is she eating normally, and is her food formulated for mice?  The coat's quality is a result of nutrients in the food, so it could be playing a part in why it's thinning out.

Let me know if neither of these sounds right and we'll try and figure it out.
-Tam