SYMPTOMS
The skin of the nose becomes dry, thickened, and hornlike. The callused nose may crack and develop fissures, then become irritated and infected. It can stay confined to one part of the nose or encompass then entire planum nasale (the moist, black part of most dogs' noses). It may or may not also involve the pads of the feet.

ETIOLOGY AND PATHOGENESIS
Hyperkeratosis occurs as a consequence of increased production of, or retention of, dead skin tissue. Spontaneous idiopathic (unknown cause) disease, particularly of the older dog, is the most common clinical presentation. Bacterial dermatitis can be a cause. Crusting, loss of the normal reticular pattern of the planum and depigmentation may all be caused by bacterial infection. It is also important to note that chronic nasal discharge in any breed may result in the creation of a micro-environment that may predispose to secondary bacterial infections of the planum nasale.

DIFFERENTIAL DIAGNOSES

DIAGNOSTIC TESTS
Diagnosis is generally based on clinical findings. Histopathologic examination of biopsy samples is the most useful diagnostic tool.

MANAGEMENT
If a specific disease can be identified, then it should be managed accordingly. 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. The management of idiopathic disease can be difficult because of the nature of the lesions and the tendency of the animal to lick topically applied agents. However, some distraction may allow for some of the medication to be absorbed and that may be enough.
Local infection is treated with topical antibiotics, such as triple antibiotic ointment. Sometimes oral antibiotics are needed.

PREVENTION
There is no known prevention for this condition.