The uropygial gland, when present, is a bilobed holocrinc gland with secretions that perform several functions in birds, including waterproofing (although not essential for it), manufacturing vitamin D precursors, keeping the skin, feathers, and bill supple, and performing antibacterial function. Many problems with this gland are secondary to hypovitaminosis A and be corrected by moist hot packing, correcting the diet, and treating any secondary infections. Diagnostics such as cytology, biopsy, aspiration, microbiology and histopathology may be used to confirm a diagnosis. Surgery should only be attempted if medical management has been unrewarding, or if a tumor, abscess or rupture is present.