Anal pouch

The anal sac ( sinus paranalis ) is a special form of the anal glands in predators . It is a glandular collection space located on both sides, in the lower lateral area of the anus , under the external anal sphincter muscle. It has a diameter of 10–15 mm in domestic dogs and 6–8 mm in domestic cats . In dogs, however, there is great variability depending on the body size: in small dogs the volume fluctuates between 0.25 and 2.5 ml, in large dogs the volume can be up to 7.5 ml. The duct, however, has a race-independent diameter of about 1-2 mm and is about 3 to 5 mm long.

The sebum and apocrine tube glands located in the wall release their secretion into the anal pouch . This mixes with exfoliating epithelial cells and is decomposed by a bacterial flora ( Streptococcus faecalis , Streptococcus faecium ), creating strong-smelling compounds such as trimethylamines , butyric acid , propionic acid , indoles and skatoles . In cats, the holocrine glands show a seasonal variation in secretion production, which increases in spring and decreases in autumn, while the apocrine glands ensure a continuous secretion.

The duct of the anal pouch opens into a visible opening in the skin zone ( zona cutanea ) of the anus. Emptying takes place via the smooth muscles of the wall of the anal bag and the contraction of the external anal sphincter muscle during excrement. The secretion from the anal pouches gives the feces an individual fragrance.

Diseases

In dogs, and more rarely in cats, inflammation of the anal sacs and blockage of the ducts can occur. Affected animals try to empty the anal bags by sliding on their rear end, so-called "sledding". The manual squeezing out and, if necessary, rinsing and application of medication with a button cannula are common routine tasks of a veterinarian. Also tumorous changes ( adenomas and adenocarcinomas ) occur.

Chronically diseased and tumorous anal pouches are usually removed surgically.

Anal sac abscess
Anal pouch carcinoma

literature

H. Geyer: Specific skin glands. In: Salomon et al. (Hrsg.): Anatomie für die Tiermedizin . Enke, Stuttgart 2004, ISBN 3-8304-1007-7 , pp. 641-645.

Individual evidence

↑ ^a ^b Johann Rinck et al.: Morphometric examinations of the anal sacs (sinus paranales) in dogs. In: Small Animal Practice. 45 (2000), pp. 927-931.
↑ Maria F. Flachsbarth et al.: The anal pouch of the house cat - a contribution to the functional morphology of a chemo-communication organ. In: Small Animal Practice. 37: 231-236 (1992).

[Rinck-1] Johann Rinck et al.: Morphometric examinations of the anal sacs (sinus paranales) in dogs. In: Small Animal Practice. 45 (2000), pp. 927-931.

[2] Maria F. Flachsbarth et al.: The anal pouch of the house cat - a contribution to the functional morphology of a chemo-communication organ. In: Small Animal Practice. 37: 231-236 (1992).