Hi there and thank you for using Pet Coach! From the picture you have attached, I would suspect a bacterial skin infection, chronic wound, burn or contact dermatitis from something irritating. I would have this examined by a veterinarian in order to determine what this could be by testing this further. Pete will likely require oral antibiotics and topical treatment for appropriate therapy. I hope this helps! Please let me know if you have any other questions or concerns. I am also available via phone or text based consultation if needed.