Equine Melanotic Disease

After a description of the morbid anatomical and histological appearances of equine melanotic disease, the author provides a critical review of the literature. The histogenesis is demonstrably via dermal melanocytic proliferation. By comparing the equine disease with spontaneously occurring and chemically induced dermal melanocytic tumours in the hamster, and with the wide range of behaviour pattern seen in the human blue naevus, also the subject of a review, he concludes that equine melanotic disease is best considered as a special manifestation of the blue naevus phenomenon.