Melanomas that occur in hairy places are usually not malignant, in contrast to those on the transition between skin and mucous membrane. Benign melanomas of the skin are well defined, highly pigmented, small and mobile. Malignant skin melanomas appear to be larger (> 2.5 cm), grow quickly and can ulcerate.
Melanomas that occur on hairy skin make up 5-7% of all skin tumors in dogs. These tumors arise from pigment cells in the epidermis, dermis, structures closely associated with the skin, but mainly arise from the hair follicles.
This tumor type affects mainly dogs between 5-11 years of age (average age: 9 years).
The following breeds were reported to be at higher risk to develop this tumour type: i.a. Airedale Terrier, Boston Terrier, Cocker Spaniel, Miniature Schnauzer, Doberman Pinscher, Scottish Terrier, Magyar Vizsla.
Skin melanomas vary in their appearance. Generally, a melanoma forms one solid lump, and the colour of the melanoma can take on a variety of colours, ranging from black to shades of brown, gray, and red.