Thank you! This is most indicative of mucocutaneous pyoderma which is a bacterial infection of mucocutaneous junctions (such as where the mucous membranes of the oral cavity meet the skin). It's uncommon in dogs; German shepherds and their crosses are possibly predisposed, indicating possible association with the ulcerative syndromes of German shepherds (mucocutaneous pyoderma, perianal fistula, metatarsal ulceration). Lesions are characterized by some combination of mucocutaneous swelling (quite apparent in Bandha), erythema (reddening/quite apparent), and crusting, often bilateral and sometimes symmetrical. Affected areas may be painful or pruritic (itchy), and self-traumatized; they may become exudative, eroded, ulcerated, fissured, and depigmented. The margins of the lips, especially at the commissures, are most frequently affected.
Treatment is as follows:
1) For mild to moderate lesions, affected areas should be clipped and cleaned with shampoo that contains chlorhexidne.
2) Topical prescription mupirocin ointment or cream should be applied every 12-24 hours for 1 week, then every 3-7 days for maintenance therapy, as needed.
3) For severe lesions, in addition to topical therapy, appropriate systemic antibiotics should be administered for 3 weeks.
4) The prognosis is good if an underlying primary disease (allergy, endocrinopathy) can be identified and controlled but lifelong maintenance therapy is often needed. If regularly applied, topical antibiotics may maintain remission.
Feel free to share our conversation with Bandha's vet. The top differentials are superficial pyoderma, lip fold pyoderma, autoimmune skin disorders (unlikely if it has responded nicely to only antibiotics), demodicosis (the Demodex mange mite), dermatophytosis (fungal infection), Malassezia (yeast) dermatitis, candidiasis, and epithliotropic lymphoma (not a consideration because it has responded to antibiotics). Please continue our conversation if you wish.