Activation of melanogenesis in the beagle by a vasodilator, mecinarone

Mecinarone (18.25 mg/kg twice a day orally for 6 months) induces an increase in melanin content of pigmented skin and mucosae in the Beagle dog. This effect is reversible. This effect is not due to a central or an endocrine mechanism because plasma levels of M.S.H., A.C.T.H. and cortisol remain normal. High levels of Mecinarone are found in melanized areas (skin, hair and non tapetal area of the eye). This effect is reversible. In contrast wih the Beagle, studies in pigmented guinea-pig and rabbit have been negative.