Deer Losing Hair - mainly around neck

Today I visited my deer Rosa and her pals.

My Rosa has never looked so awful to me. I noticed about a month ago, when we had extreme heat that her hair was beginning to thin our a lot around her neck.



I looked really closely and didn't notice any type of lice or any other topical issues other than hair that had begun to fall off and thin.



I de-wormed her with Cydectin topical. A week later, when I returned she looked OK, was active, although her hair had fallen off more around her neck.



Today her hair was almost bald in certain spots around her neck, top part and under her chin, leading to her chest. Also near her tail.



No deer are with her in her pen, so it is not a result of other deer pulling out her hair. Also, since it is under her neck and on top of it, it cannot be a result of her pulling out her own hair.



Please, deer people, what can be causing this?



Her pellets are great, she is eating well, and is not thin at all. Seems OK otherwise.



Any ideas or input of any kind, no matter how trivial it may seem, is welcome.



Thank you,

lana

Rosa can't stick her head out of the fence anywhere b/c there is shade cloth everywhere.

Her neck is basically pinkish, but the top of her back (near her rear end)- is black skin. I attribute the black color to having a really good suntan.



One other thing I forgot to mention, there are NO TREES in my Rosa's permanent pen...



Could overexposure to sunlight be doing this to her?



Her neck is almost bare all the way around. It makes me very sad. I wish that I could find a better place for her.

By the way, the genius farmers who own the pens have baby raccoons in the pen adjacent to my Rosa.

Scott, you've taken a load off of my worrying. Thank you so much for responding to my question- I really appreciate it. Big big big hug to all who've tried to help me. I will post pic's next wkd. when I see my doe again.