Also known as: Nodular sebaceous hyperplasia

Transmission or cause: A benign tumor of the oil gland (sebaceous) cells of the skin. Although these tumors are commonly called “old dog warts” due to their appearance, they are not true warts as they are not viral-induced.

Clinical signs: Single to multiple raised, hairless, lobulated white to pale pink skin or sometimes pigmented skin masses which may ooze an oily white material. Masses range in size from ¼” – 1” in diameter. Tumors occur most commonly on the trunk, legs, feet or face. They usually cause no bothersome symptoms unless they become traumatized or secondarily infected, in which case the dog may lick or chew at the lesions.

Diagnosis: Most commonly diagnosed by clinical presentation, but definitive diagnosis requires a biopsy, which reveals a benign accumulation of neoplastic sebaceous cells.

Treatment: In most cases aggressive treatment is not needed, as these are cosmetic lesions. However lesions which grow, change or bother the dog should be removed and biopsied. Surgical removal is curative but new nodules often continue to form elsewhere as the dog ages. In dogs with numerous tumors, oral retinoids (ie. isotretinion) may slow growth of nodules and decrease formation of new tumors.

Prognosis: Good, as these tumors are benign, however new tumors tend to occur as the dog ages.