Thank you! Those pics represent a chin pyoderma (also called canine acne). Chin pyoderma is a bacterial infection that isn't a true acne but rather is a traumatic furunculosis. Short, stiff hairs are forced backward through the hair follicle, creating a sterile foreign body reaction that may become subsequently infected. This may be induced by trauma to the chin (e.g., caused by lying on hard floors, friction from chew toys). It's common in short-coated dogs, especially when 3-12 months old.
Treatment and prognosis is as follows:
1) Trauma and pressure to the chin should be minimized.
2) The area should be scrubbed with benzoyl peroxide or chlorhexidine shampoo in the direction of hair growth. This mechical scrubbing to remove "ingrown hairs" is important for preventing future lesions and speeding resolution. These shampoos are available over the counter in pet/feed stores or at Lulu's pet hospital.
3) The prescription mupirocin ointment or benzoyl peroxide gel (available over the counter) should be applied every day until lesions resolve, then every 3-7 days as needed for control. If response if poor, systemic antibiotics should be administered for a minimum of 4-6 weeks and continued 2 weeks beyond complete clinical resolution.
4) Adhesive tape (Elasticon, e.g.) can be used to tape strip the "ingrown hairs" making hair removal easy.
5) The prognosis is good. In many dogs the lesions resolve permanently; however, some dogs require lifelong routine topical therapy for control.
Please continue our conversation if you wish.