Uropygial or Preening Gland in Birds

What is a uropygial gland?

Among pet birds, the uropygial gland (preening gland, preen gland, or oil gland) is found on parakeets, cockatiels, canaries, most species of parrots, most finches, cockatoos, and waterfowl. It is absent in doves, pigeons, Amazon parrots, and Hyacinth macaws.

The uropygial gland is located on top of the tail base, on the lower back, just in front of the base of the tail feather quills. This area is generally featherless except for a tuft of feathers at the tip called the uropygial wick. The gland is bi-lobed, with two similar-sized sections.

The uropygial gland secretes a thick, transparent, complex oil (preening oil) that consists of diester waxes (uropygiols), fats, and fatty acids. Each lobe of the gland secretes oil through small papilla (nipple-like projections).

The oil secreted by the uropygial gland performs many functions, including waterproofing and maintaining the suppleness of the skin, feathers, and beak. The oil may have an antibacterial function. 

During preening, a bird transfers this oil to its feathers by rubbing its head and beak against the oil gland and then spreading the oil over the rest of its feathers.

The uropygial gland is not normally visible unless the feathers are parted in this area or there is a problem with the gland.

What problems can occur with the uropygial gland?

Vitamin A deficiencies, which occur commonly in parrots on a predominantly seed-based diet, may lead to a blockage of the papilla, which causes the gland to enlarge. The blockage may form due to the abnormal thickness of the oil, due to dehydration, or it may be due to improper shedding of cells that line the inside of the gland, due to vitamin A deficiency.

When the papilla becomes blocked, the glands become swollen and may become irritating to the bird, causing them to pluck feathers around the gland. The blockage must be addressed by an avian veterinarian. In mild cases, the plug/blockage may be resolved by applying warm water compresses to the uropygial gland to help liquify the plug/blockage. To prevent a recurrence of the problem, it is essential to correct the diet imbalance and increase vitamin A intake.

Various tumors occur in the uropygial gland and may require surgical correction. Parakeets (budgerigars) and cockatiels are prone to squamous cell carcinoma or preen gland adenocarcinoma of the uropygial gland. These cancerous growths of the uropygial gland often protrude above the feathers on top of the tail. Chemotherapy and/or cryotherapy have been used successfully on squamous cell carcinoma.

Infections may also occur, but these are often secondary to vitamin A deficiency, trauma, or immunosuppression, such as occurs with Psittacine Beak and Feather Disease (PBFD). If you have any concerns, discuss them with a veterinarian familiar with birds.