CHAPTER | 11 Pigmentary Abnormalities
Lentigo
Features
Lentigo is an asymptomatic condition characterized by one (lentigo) or more (lentigines) flat macule(s) or patch(es) of black skin. It is common in dogs, with highest incidences reported in middle-aged to older dogs. It is uncommon in cats, with the highest incidence in young orange cats.
Dogs
In dogs, lentigo appears as one or more macular to patchy areas of hyperpigmented skin. Lesions are most commonly found on the ventral abdomen and chest.
Postinflammatory Hyperpigmentation
Features
In postinflammatory hyperpigmentation, skin (melanoderma) or hairs (melanotrichia) become hyperpigmented as a sequela to an underlying skin disease such as pyoderma, demodicosis, dermatophytosis, or hypersensitivity. This hyperpigmentation may be focal and circumscribed, patchy, or diffuse. It is common in dogs and uncommon in cats.
Treatment and Prognosis

FIGURE 11-3 Postinflammatory Hyperpigmentation.
Generalized hyperpigmentation associated with resolving erythema multiforme.
Nasal Depigmentation (Dudley nose, snow nose)
Features
Nasal depigmentation is an idiopathic disorder in which affected dogs are born with a pigmented nose, which later in life lightens to a light brown or whitish color. Nasal depigmentation may wax and wane, may be seasonal, may resolve spontaneously, or may be a permanent change. Only the nose is affected, and the normal cobble texture of the nose is preserved (autoimmune skin diseases destroy the normal architecture). It is common in dogs, with the highest incidence in Golden retrievers, yellow Labrador retrievers, Siberian huskies, and Alaskan malamutes.
Dudley nose usually describes a permanent pigmentary defect (undesirable show fault), whereas snow nose describes transient, seasonal depigmentation changes.

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