The violet gland or supracaudal gland is an important gland located on the upper surface of the tail of certain mammals, including European badgers and canids such as foxes, wolves the domestic dog, as well as the domestic cat is used for intra species signalling, scent marking, and contributes to the strong odor of foxes in particular.
Although it secretes a mixture of volatile terpenes similar to those produced by violets (hence the name), the chemicals are produced in much greater quantity than in flowers and the resulting strong smell can be quite unpleasant. Like many other mammalian secretion glands, the violet gland consists of modified sweat glands and sebaceous glands.
In the European badger, the secretions of the violet gland contain a high concentration of lipids, with a composition that varies seasonally. Researchers at the University of Oxford have identified 110 compounds produced by the violet gland using gas chromatography. It was found that specific compositions were shared among groups of badgers, while the secretions of individual badgers varied according to age, gender, health, and reproductive status.
In foxes, the violet gland is found on the upper surface of the tail, at roughly one-third of the tail's length from the body, and measures about 25 by 7.5 millimeters in red foxes. Due to its role in steroid hormone metabolism (and possibly production), foxes cannot be "de-scented" by removing this gland. For unknown reasons, the gland's secretions are fluorescent in ultraviolet light; this may result from the presence of carotenoids.
In dogs, the violet or supracaudal gland is found approximately above the 9th caudal vertebra. 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 appears in both genders.
Some dogs exhibit a bald spot at the side of the violin gland. In most cases, the hairs grow again automatically. In the spring when the nose will be 'sexually stimulated/arouse', through the air from the many females in heat this process can be repeated. Puberty of the dog plays a big role.
Note, that the bare, unprotected skin is not to dry. Treat and rub with 'Tree Trea Oilment' gives good results and has a healty effect. Often the dog licks after application so it is recommended to do this before you walk the dog.
The wolf stabbing is not discribed in the breed standard of the Ca de Bou although it is a 'typical' appearance for the race. In dogs with fawn color the sign will be more noticable than a brindle dog.
As the pup grows most of the time the 'mark' will disappear, but in some cases the 'mark' will always remain visible.
A Rhodesian Ridgeback (sex unknow) with
stud tail the violet gland lost hair and appears
as a dark dimple.