losing coat/hairloss/itching

Question
I have a 3yr old intact female Holland Lop who is losing lots of fur/coat. She is housed outdoors all year long in my screened in porch. I live in Wisconsin and we are slowly heading into our very cold season. She first exhibited itching with some heavy crusting on her rump area. My first though was Cheyletiella. I am a vet tech and I did look at samples of fur/skin under the microscope and did NOT find any eggs/mites. I did go ahead and treat her with selemectin (0.2cc - she is apprx 2.8kg/5lbs) 3 times. First time was just one dosing, but when the itching resumed, I treated her 2 more times, 2 weeks apart. Seemed to help with itching and heavy scale, but now, she is blowing so much coat, and has areas of fur loss - but has new fur growth underneath. I did NOT treat her housing area. She sleeps in a hutch at night but has free roam of my porch, which is covered with outdoor carpeting. My porch is elevated, no contact with vegetation, and my rabbit never has been in grass. As I mentioned, we are heading into our snowy season, and she will be outdoors (this will be her 3rd winter outside) and will need her coat. Can you offer any advice on this situation? Can I prophylatically treat her with selemectin since I cannot treat/clean the environment? SHOULD I try to clean the environment and if so, with what and not kill her with. She is a very spoiled bunny despite being outdoors. She has a heated water bowl, heated bedding, gourmet greens/fruit 2X/day, and now gets oatmeal w/ her pellets to add weight for the upcoming winter. Is there a supplement that may help her? Her next treament of selemectin is due next week if I am to continue the every 2 week treatment. THANK YOU for your help!

Answer
hi susan i would not give her anything ,justlet her get on with getting her winter coat and see how it goes-with the diet she is on she does not want a supplement as she is getting all she needs.
if her coat does not change as it should  she may need further tests to find out exactually what is going on.
dave.