Image Quiz: A Lab with a penile mass

A 3-year-old male Labrador retriever was presented for evaluation because of blood dripping from its penis as a result of a large, friable, bloody, cauliflower-like mass in the region of the bulbus glandis (photo courtesy of Tanya Hall, DVM). An impression smear stained with Wright-Giemsa stain is shown (50X magnification).

What would be the most effective treatment of this lesion?

a) Antibiotics

b) Vincristine

c) Prednisone

d) Surgical excision