Hello & welcome, I am Dr. B, a licensed veterinarian and I would like to help you today. I do apologize that your question was not answered before. Different experts come online at various times; I just came online, read about your wee one’s situation, and wanted to help.
Again I do apologize that my colleagues could not aid you sooner, but can you tell me:
How long has this been going on?
Any pimples, pustules, scabs, sores, ulcers, dander, or crusting in the raw area?
When did you last treat for fleas? What did you use?
Any diet change in the 4-6 weeks before this started?
Is his puppy in direct contact with Duke?
Can you post the photo you took so that I can see what you are seeing. To post them online, you can use the paper clip icon above your text box. Or if you cannot see that on your phone/computer, just post them on any site (ie Flickr, Photobucket, Imgr etc) and paste the web link here for me follow.