Aloha! You're speaking with Dr. Michael Salkin
I'm sorry that your question wasn't answered in a timely manner. I understand the logistical constraints you might have presumptively treating these ferals. Can you upload a photo of Barney's representative skin to our conversation? You can use the paperclip icon in the toolbar above your message box (not if you're using the chrome browser) or you can use an external app such as imgur.com or dropbox.com. I can be more accurate for you if I can see what you're seeing.
Please tell me which flea treatment was used. A flea saliva allergy must always be considered when pruritis
(itchiness) and hair loss is seen in the "saddle" area. Atopy - allergies to environmental allergens such as pollens, molds, dust, and dust mites, etc. might be incriminated and addressed with an over the counter antihistamine such as diphenhydramine (Benadryl) dosed at 1-2 mg/lb every 12 hours. Antihistamines aren't reliably effective in atopic cats but worth a try if you don't have a corticosteroid such as prednisone at home.
Sarcoptic mange is less likely as it causes a progressive and intense pruritis beginning on the ears
and moving on to areas about the face and the around the rest of the body. Demodectic mange isn't as common but should remain on my differential diagnosis list.
A fungal infection (ringworm
) needs to be considered but is addressed with lime sulfur dips and oral prescription antifungal drugs such as fluconazole or itraconazole. I don't recommend either treatment unless ringworm is confirmed with a fungal culture.
intolerance might have arisen. This would be problematic for you to confirm with a hypoallergenic food trial because a feral can't be expected to eat only the presumptively hypoallergenic diet. Please respond with further questions or concerns if you wish.