My four year old female rabbit started showing signs of mites in March, I gave her two rounds of ivermectin, 18 days apart, the last dose being on April 1. Since then her hair has begun to fall out and she has scaly patches on her skin. Any advice would be appreciated, thank you!
Wow, that's pretty extreme, poor thing. I'm amazed that ivermectin didn't take care of it, if it really is mites.
What kind of ivermectin did you give her, how did you apply it (topically or orally), and how much did you give her?
Did you identify where the mites might have come from (straw, hay, another rabbit, etc.)? Is she in a place she could have been reinfected after the ivermectin was eliminated from her system? Did you completely clean out her cage and get rid of all bedding and sterilize all of her things?
Have you been able to actually see any mites? Some fur mites are big enough to see without a microscope, but even with some of the smaller ones you can sometimes see movement with a magnifying glass. It surely does look like mites with all that flaking, but I suppose it could be ringworm, which is a fungal infection. With the length of her problems, there could also be more than one thing going on.
I've never heard of it happening with ivermectin, but there is always a chance that an individual can have an allergy or intolerance to any drug, so that's another possibility.
A bit more information might help one of us out here more able to offer useful suggestions.