The tail gland of canids is a hepatoid glandular organ surrounded and penetrated by powerful hair erector muscles squeezing out its lipoprotein secretion onto the skin surface. The gland is most developed in solitary species (Arctic, red, and corsac foxes) where it is represented by powerful glandular layer with large secretion containers—cisterns. It is less developed in the jackal; there are cisterns but glandular lobes do not merge into a layer. In the raccoon dog, wolf, and domestic dog the gland is composed of small lobes without cisterns. Hepatoid glands of the tail gland are represented by two histological variants distinguished by the presence or absence of hydrophobic lipids in the secretory cells. The excretory ducts are formed by lipid transformation of the cellular bands.