Violet gland

In dogs, the violet or supracaudal gland is found approximately above the 9th caudal vertebra, but depending on breed it may be vestigial or entirely absent.

The violet gland secretes protein and hydrophobic lipids, has wide excretory ducts, is connected with coarse hairs, devoid of cysts, and has no sexual dimorphism.

In the dog and cat fancy it is often referred to as "stud tail", despite the fact that it occurs in both sexes, not just breeding males.

However, for reasons still unknown the hair at a dog's violet gland tends to fall out when androgen levels are high over a prolonged time.

Due to its role in steroid hormone metabolism (and possibly production), foxes cannot be "de-scented" by removing this gland.