This disease occurs in old dogs. The cause is unknown. The skin of the nose becomes dry, thickened, and hornlike. The callused nose may crack and develop fissures, then become irritated and infected. Hyperkeratosis can also occur in association with zinc-responsive dermatosis, pemphigus foliaceus, and discoid lupus erythematosus.
Hard pad is a related condition involving the nose and foot pads; it occurs as a sequel to canine distemper. As the dog recovers from distemper, the nose often regains its normal appearance.
Treatment: There is no cure for idiopathic nasal callus. Control is aimed at softening the nasal callus with wet dressings and keeping the nose well lubricated with mineral oil, aloe, or petroleum jelly. Local infection is treated with topical antibiotics, such as triple antibiotic ointment.