Some replies from Dr.'s and specialists:
"From what I have seen of the photos, it looks like it could be many things. Vitamin A deficiency (not very likely), biotin eficiency (also not very likely), zinc deficiency (it could be this one) or an auto immune disorder such as pemphigus or lupus. I would continue to treat her with vitamins and make sure that there is zinc in with the supplements. If she doesn't get better in a month, she probably won't get better because it is her body attacking her skin."
"Sorry
saw your later email before this one. I doubt if there is going to be any treatment as you have tried just about everything possible. The best bets are the topical use of tea tree oil and an injectable b-complex. I worry that even though biotin was tried, other b-vitamins could be involved, and the bird may not be able to absorb them for some reason. A local vet could set you up with a regimen like this. The probability that anything like this would work is admittedly low, and, if it did, it would probably need to be continued for the life of the bird as it is likely not going to recover. This disease is likely systemic and only the external effects of the disease are apparent
changes are likely underway internally, which are responsible for the slowed growth and development of this bird. If the decision is made to put the bird to sleep, it would be very helpful to have a necropsy (autopsy) done to see if anything can be learned about what this disease is."
"I think a couple more toes are going to slough off as well if the bird lives much longer. This disorder could very well be affecting internal organs as well."
"I was talking briefly to "colleague" and agree with him as far as a genetic predisposition. One thing though, is that there may be a genetic predisposition to be susceptible to a specific nutritional deficiency, so even though most birds in your environment would have no problems, one that had a bit of a genetic disadvantage might be susceptible. I was wondering if you could tell me what the standard diet currently is for your birds and if it is from multiple sources roughly what percentage comes from each feed item. (i.e. commercially prepared feed Mazuri brand 70%, foraging 15%, table scraps 15%, etc.)"
"I do not recall seeing anything like this before. I believe you are correct that this is most likely a genetic disorder in this individual bird. I have forwarded your material to "colleague", who is a pathologist on our faculty and an international expert on skin disorders. After he has had a chance to evaluate the pictures, I would be interested in discussing the case with you further. I will be back in touch soon."
If I hear more, I will update again.
J.