Mange

I'm fairly sure this pretty little fox has mange, a parasitic mite that burrows into skin making it very itchy and causing hair loss, subsequent scratching aggravating more hair loss. Can be so painful that an animal doesn't eat well or even search for food, leading to death.

 

You can see the areas this fox is able to reach with her teeth, for scratching, are suffering quite a bit of hair loss, on her tail and hindquarters.

 

Damn.

Done