So poor Exidor is suffering from some baldness on his back, in an area he can't reach easily. I waded through some truly heartbreaking photos and descriptions of various bunny skin diseases on the internet, but none matched his symptoms: he has no redness, no itching, no crusty stuff anywhere. Just a big and ever expanding bald area on his back.
Turns out overgrooming by a bonded mate can cause this... and I have seen Cleo groom him pretty obsessively. And they are definitely bonded. They sleep in a little pile and groom one another all the time. I had suspected she might be just wearing his fur right off but wanted to get some validation elsewhere. The cure: exercise, toys, distractions. So, we are going to borrow a no-longer-needed kid enclosure that we're pretty sure J's sister still has and see if that contains them, and if not we'll find something else for the indoor exercise. I want something kind of enclosure-y because I find that just cordoning off part of the house is not sufficient, in that it takes me twenty minutes to catch the little dears when it's time for them to go back into their hutch.
Hurrah! He doesn't have the mange!