The two affected does are 3 and 5. Both are lactating. Over the course of this past week their coats have been looking progressively rougher and they've progressed to frank hair loss especially around the withers and a bit on the top line. One has a great deal of skin flaking, but neither seem excessively itchy. They live with nursing kids and yearlings who are unaffected. We just moved, and I'm concerned about parasites or that the new well water may be inhibiting some mineral uptake.
They have access to loose mineral and are fed a 16% balanced textured feed with added BOSS and free choice second cut hay, and I've added a bit of calf manna to help them maintain condition. They are due to be copper bolused but I'm afraid to do it right now in case this is zinc deficiency because I know the copper would inhibit the zinc.
The vet hasn't seen them in person, but guessed from the pictures it may be mites. There are no visible lice or nits. I'm terrified to death because I've never seen anything like this before. It was so sudden. How would you proceed here?