Anal gland

The anal glands or anal sacs are small glands near the anus in many mammals, including dogs and cats. They are paired sacs on either side of the anus between the external and internal sphincter muscles. Sebaceous glands within the lining secrete a liquid that is used for identification of members within a species. These sacs are found in many carnivorans, including wolves,[1] bears,[2][3] sea otters[4] and kinkajous.[5]

Humans

Gray1080
Diagram showing anal canal, with dentate line, along which anal crypts open. Anal glands drain into anal crypts via anal ducts. Note also intersphincteric plane where some of these glands are located.

The anal glands are in the wall of the anal canal. They secrete into the anal canal via anal ducts which open into the anal crypts along the level of the dentate line. The glands are at varying depths in the anal canal wall, some between the layers of the internal and external sphincter (the intersphincteric plane). The cryptoglandular theory states that obstruction of these ducts, presumably by accumulation of foreign material (e.g. fecal bacterial plugging) in the crypts, may lead to perianal abscess and fistula formation.[6][7]

Dogs

Anal gland abscess
Anal gland abscess on a dog

In dogs, these sacs are occasionally referred to as "scent glands", because they enable the animals to mark their territory and identify other dogs. Most small dogs and many large ones too will need their anal sacs expressed at some stage of their lives. Anal sac expression should be performed to maintain the dog's hygiene, for instance if the fluid leaks spontaneously and to eliminate discomfort. Discomfort is evidenced by the dog dragging its posterior on the ground ("scooting"), licking or biting at the anus, sitting uncomfortably, having difficulty sitting or standing, or chasing its tail. In some dogs the sacs can spontaneously empty, especially under times of stress, and create a very sudden unpleasant change in the odor of the dog. Dog feces are normally firm, and the anal sacs usually empty when the dog defecates. When the dog's stools are soft they may not exert enough pressure on the glands, which then may fail to empty. This may cause discomfort as the full anal sac pushes on the anus. The sacs can be emptied by the dog's keeper, or by a groomer or veterinarian. The sacs are emptied by squeezing the sac so the contents are released through the small openings (ducts) on either side of the anus. This technique is known as anal sac expression. Discomfort may also be evident with impaction or infection of the anal glands. Anal sac impaction results from blockage of the duct leading from the gland to the opening. The sac is usually non-painful and swollen. Anal sac infection results in pain, swelling, and sometimes abscessation and fever. Treatment often involves frequent expression of the sac and systemic antibiotics. Occasionally treatment may include, lancing of an abscess or antibiotic infusion into the gland in the case of infection. The most common bacterial isolates from anal gland infection are E. coli, Enterococcus faecalis, Clostridium perfringens, and Proteus species.[8]

Anal sacs may be removed surgically in a procedure known as anal sacculectomy. This is usually done in the case of recurrent infection or because of the presence of an anal sac adenocarcinoma, a malignant tumor. Potential complications include fecal incontinence (especially when both glands are removed), tenesmus from stricture or scar formation, and persistent draining fistulae.[9]

Anal sac fluid varies from yellow to tan or even brown in color and watery to could be kind of thick in consistency, yet still easily expressible. Impacted anal glands can be identified by the material usually being very thick, most times gritty or not being able to express anal sacs altogether without serious pain or damage. The presence of blood or pus indicates infection.

Cats

As with dogs, a cat's anal glands can spontaneously empty, especially under times of stress, and create a very sudden unpleasant change in the odor of the cat. A cat's glands may become impacted, causing the cat to defecate outside the litter box, almost anywhere in the house. A veterinarian can empty the clogged glands, and defecating outside the litter box will stop immediately in most cases. Often this problem is incorrectly interpreted as behavioral, when it is entirely a problem of clogged or blocked anal glands or difficulty defecating.

Opossums

Opossums use their anal glands when they "play possum". As the opossum mimics death, the glands secrete a foul-smelling liquid, suggesting the opossum is rotting. Note that opossums are not members of the carnivora, and that their anal sacs differ from those of dogs and their relatives.

Skunks

Skunks use their anal glands to spray a foul-smelling and sticky fluid as a defense against predators.

Beavers

An extraction of castoreum, the scent glands from the male and female beaver is used in perfumery and as a flavor ingredient.

See also

References

  1. ^ L. David Mech; Luigi Boitani (1 October 2010). Wolves: Behavior, Ecology, and Conservation. University of Chicago Press. ISBN 978-0-226-51698-1.
  2. ^ Rosell, F.; Jojola, S. M.; Ingdal, K.; Lassen, B. A.; Swenson, J. E.; Arnemo, J. M.; Zedrosser, A. (Feb 2011). "Brown bears possess anal sacs and secretions may code for sex". Journal of Zoology. 283 (2): 143–152. doi:10.1111/j.1469-7998.2010.00754.x.
  3. ^ Dyce, K.M.; Sack, W.O.; Wensing, C.J.G. (1987). Textbook of Veterinary Anatomy. W.B. Saunders Company. ISBN 0-7216-1332-2.
  4. ^ Kenyon, Karl W. (1969). The Sea Otter in the Eastern Pacific Ocean. Washington, D.C.: U.S. Bureau of Sport Fisheries and Wildlife.
  5. ^ Ford, L. S.; Hoffman, R. S. (1988-12-27). "Potos flavus". Mammalian Species. American Society of Mammalogists. 321: 1–9. doi:10.2307/3504086. JSTOR 3504086.
  6. ^ Yamada, Tadataka; Alpers, David H.; Kalloo, Anthony N.; Kaplowitz, Neil; Owyang, Chung; Powell, Don W., eds. (2009). Textbook of gastroenterology (5th ed.). Chichester, West Sussex: Blackwell Pub. ISBN 978-1-4051-6911-0.
  7. ^ Wolff, Bruce G.; Pemberton, John H.; Wexner, Steven D.; Fleshman, James W.; Beck, David E., eds. (2007). The ASCRS textbook of colon and rectal surgery. New York: Springer. ISBN 0-387-24846-3.
  8. ^ Ettinger, Stephen J.; Feldman, Edward C. (1995). Textbook of Veterinary Internal Medicine (4th ed.). W.B. Saunders Company. ISBN 0-7216-6795-3.
  9. ^ Hill LM, Smeak DD (2002). "Open versus closed bilateral anal sacculectomy for treatment of non-neoplastic anal sac disease in dogs: 95 cases (1969–1994)". J Am Vet Med Assoc. 221 (5): 662–5. doi:10.2460/javma.2002.221.662. PMID 12216905.

External links

Aardwolf

The aardwolf (Proteles cristata) is a small, insectivorous mammal, native to East and Southern Africa. Its name means "earth-wolf" in Afrikaans and Dutch. It is also called "maanhaar-jackal" (Afrikaans for "mane-jackal"),"ant hyena" or civet hyena, based on its habit of secreting substances from its anal gland, a characteristic shared with the African civet. The aardwolf is in the same family as the hyena. Unlike many of its relatives in the order Carnivora, the aardwolf does not hunt large animals. It eats insects and their larvae, mainly termites; one aardwolf can lap up as many as 250,000 termites during a single night using its long, sticky tongue.The aardwolf lives in the shrublands of eastern and southern Africa – open lands covered with stunted trees and shrubs. It is nocturnal, resting in burrows during the day and emerging at night to seek food.

Anal canal

The anal canal is the terminal part of the large intestine. It is situated between the rectum and anus, below the level of the pelvic diaphragm. In humans it is approximately 2.5 to 4 cm (0.98-1.58 in) long. It lies in the anal triangle of perineum in between the right and left ischioanal fossa.

The anal canal is the short terminal portion of the rectum through which wastes from the large intestine are excreted from the body. The ring at the terminal portion of the anal canal is called the anus.

The anal canal is between 2.5 cm and 5 cm in length and is guarded by two muscles that control the release of waste from the rectum.

The external anal sphincter muscle is the voluntary muscle that surrounds and adheres to the anus at the lower margin of the anal canal. This muscle is in a state of tonic contraction, but during defecation, it relaxes to allow the release of feces.

Movement of the feces is also controlled by the involuntarily controlled internal anal sphincter which an extension of the circular muscle surrounding the anal canal. It relaxes to expel feces from the rectum and anal canal.

Anal canal is divided into three parts. The zona columnaris is the upper half of the canal and is lined by simple columnar epithelium. The lower half of the anal canal, below the pectinate line, is divided into two zones separated by Hilton's white line. The two parts are the zona hemorrhagica and zona cutanea, lined by stratified squamous non-keratinized and stratified squamous keratinized epithelium, respectively.

In humans it is approximately 2.5 to 4 cm long, extending from the anorectal junction to the anus. It is directed downwards and backwards. It is surrounded by inner involuntary and outer voluntary sphincters which keep the lumen closed in the form of an anteroposterior slit.

Behind this lies the anal gland which secretes lymphal discharge and built up fecal matter from the colon lining. In animals,

gland expungement can be done routinely every 24 – 36 months to prevent infection and fistula formation.

It is differentiated from the rectum by the transition of the internal surface from endodermal to skinlike ectodermal tissue.

Anal sac adenocarcinoma

An anal sac adenocarcinoma is an uncommon and aggressive malignant tumor found in dogs that arises from the apocrine glandular tissue of anal sac. The disease exists in cats as well, but is much less common in that species. They are the second most common cancerous cause of hypercalcaemia (high serum calcium) in dogs, following T-cell lymphoma.

Beaver

The beaver (genus Castor) is a large, primarily nocturnal, semiaquatic rodent. Castor includes two extant species, the North American beaver (Castor canadensis) (native to North America) and Eurasian beaver (Castor fiber) (Eurasia). Beavers are known for building dams, canals, and lodges (homes). They are the second-largest rodent in the world (after the capybara). Their colonies create one or more dams to provide still, deep water to protect against predators, and to float food and building material. The North American beaver population was once more than 60 million, but as of 1988 was 6–12 million. This population decline is the result of extensive hunting for fur, for glands used as medicine and perfume, and because the beavers' harvesting of trees and flooding of waterways may interfere with other land uses.

Brown hyena

The brown hyena (Hyaena brunnea), also called strandwolf, is a species of hyena found in Namibia, Botswana, western and southern Zimbabwe, southern Mozambique and South Africa. It is currently the rarest species of hyena. The largest remaining brown hyena population is located in the southern Kalahari Desert and coastal areas in Southwest Africa.

Common dwarf mongoose

The common dwarf mongoose (Helogale parvula), sometimes just called the dwarf mongoose, is a small African carnivore belonging to the mongoose family (Herpestidae). It is part of the genus Helogale and as such related to Helogale hirtula.

Dear enemy effect

The dear enemy effect or dear enemy recognition is an ethological phenomenon in which two neighbouring territorial animals become less aggressive toward one another once territorial borders are well-established. As territory owners become accustomed to their neighbours, they expend less time and energy on defensive behaviors directed toward one another. However, aggression toward unfamiliar neighbours remains the same. Some authors have suggested the dear enemy effect is territory residents displaying lower levels of aggression toward familiar neighbours compared to unfamiliar individuals who are non-territorial "floaters".The dear enemy effect has been observed in a wide range of animals including mammals, birds, reptiles, amphibians, fish and invertebrates. It can be modulated by factors such as the location of the familiar and unfamiliar animal, the season, and the presence of females.

The effect is the converse of the nasty neighbour effect in which some species are more aggressive towards their neighbours than towards unfamiliar strangers.

Dolichoderinae

Dolichoderinae is a subfamily of ants, which includes species such as the Argentine ant (Linepithema humile), the erratic ant, the odorous house ant, and the cone ant. The subfamily presents a great diversity of species throughout the world, distributed in different biogeographic regions, from the Palearctic, Nearctic, Afrotropical region and Malaysia, to the Middle East, Australian, and Neotropical regions.This subfamily is distinguished by having a single petiole (no post-petiole) and a slit-like orifice, from which chemical compounds are released, rather than the round acidopore encircled by hairs that typifies the family to which it belongs, Formicidae. Dolichoderine ants do not possess a sting, unlike ants in some other subfamilies, such as Ponerinae and Myrmicinae, instead relying on the chemical defensive compounds produced from the anal gland.Of the compounds produced by dolichoderine ants, several terpenoids were identified including the previously unknown iridomyrmecin, isoiridomyrmecin, and iridodial. Such compounds are responsible for the smell given off by ants of this subfamily when crushed or disturbed.

Eoperipatus totoro

Eoperipatus totoro is a species of velvet worm of the Peripatidae family.

Ferret

The ferret (Mustela putorius furo) is the domesticated form of the European polecat, a mammal belonging to the same genus as the weasel, Mustela, in the family Mustelidae. Their fur is typically brown, black, white, or mixed. They have an average length of 51 cm (20 in), including a 13 cm (5.1 in) tail, weigh about 1.5–4 pounds (0.7–2 kg), and have a natural lifespan of 7 to 10 years. Ferrets are sexually dimorphic predators, with males being substantially larger than females.

The history of the ferret's domestication is uncertain, like that of most other domestic animals, but it is likely that they have been domesticated for at least 2,500 years. They are still used for hunting rabbits in some parts of the world, but increasingly they are kept only as pets.

Being so closely related to polecats, ferrets easily hybridize with them, and this has occasionally resulted in feral colonies of polecat–ferret hybrids that have caused damage to native fauna, especially in New Zealand. As a result, New Zealand and some other parts of the world have imposed restrictions on the keeping of ferrets.

Several other mustelids also have the word ferret in their common names, including the black-footed ferret, an endangered species.

Hyena butter

Hyena butter is a secretion from the anal gland of hyenas used to mark territory and to identify individuals by odor. The gooey substance is spread onto objects within the territory of the hyena by rubbing their posterior against the object they mark.African legends state that witches would ride hyenas and use a gourd full of hyena butter as fuel for the torches they carried through the night.

LIFT technique

LIFT technique is the novel modified approach through the intersphincteric plane for the treatment of fistula-in-ano, known as LIFT (ligation of intersphincteric fistula tract) procedure. LIFT procedure is based on secure closure of the internal opening and removal of infected cryptoglandular tissue through the intersphincteric approach. Essential steps of the procedure include, incision at the intersphincteric groove, identification of the intersphincteric tract, ligation of intersphincteric tract close to the internal opening and removal of intersphincteric tract, scraping out all granulation tissue in the rest of the fistulous tract, and suturing of the defect at the external sphincter muscle.

The procedure was developed by Thai colorectal surgeon, Arun Rojanasakul, Colorectal Division Department of Surgery, Chulalongkorn University in Bangkok, Thailand. The first report of preliminary healing result from the procedure were 94% in 2007 In 1993 Matos et al. described a technique of total anal sphincter preservation in high fistula in ano, which is based on the concept of excision of intersphincteric anal gland infection through the intersphincteric approach. This novel technique was also documented in Corman’s textbook of colon and rectal surgery. However, the technique was not widely adopted.

Between 2004 and 2005 there was a personal experience in the similar technique by group of surgeons. That technique included coring out the intersphinteric fistula tract from the external opening to the external sphincter, excision of the intersphincteric fistula tract and suture of the internal sphincter defect through the intersphincteric plane. The outcome in 20 patients was disappointing with only 9 (45%) successes. Surgeons proposed that the reasons for the unfavorable outcome include dissection in the intersphincteric plane damaging blood supply to the internal opening area, and suturing delicate ischemic areas with increased risk of suture break-down. Surgeons thought that ligation of the intersphincteric tract close to the internal opening might solve the problem. Surgeons noticed that during intersphincteric plane dissection if the internal sphincter was damaged and the anal mucosa breached, failure was common despite meticulous repair.Researchers of the procedure agree that the LIFT technique may cause some injury to internal sphincter, but theoretically LIFT causes less trauma of the internal sphincter than the other fistula operations. Matos et al. reported the technique of excision of the whole fistula tract plus primary repair, with intersphincteric plane approach for excision of the fistula tract and suturing of the internal anal sphincter defect, in 1993. However, Rojanasakul reported the ligation of intersphincteric fistula tract in 2007 with apparent satisfactory results probably due to secured closure of the internal opening. This represents a significant change from the originally described technique with improved outcomes .

List of MeSH codes (C06)

The following is a list of the "C" codes for MeSH. It is a product of the United States National Library of Medicine.

Source for content is here. (File "2006 MeSH Trees".)

List of MeSH codes (C22)

The following is a list of the "C" codes for MeSH. It is a product of the United States National Library of Medicine.

Source for content is here. (File "2006 MeSH Trees".)

Oecobiidae

The spider family Oecobiidae (also called disc web spiders) includes about 100 described species so far.

The Oecobiidae are small- to moderate-sized spiders (about 2 mm to 2 cm head-and-body length, depending on the species); the larger species tend to be desert-dwelling. The legs are unusually evenly placed around the prosoma; most other spiders have some legs directed clearly forward and the rest clearly backward, or all forward. The first two pairs of legs of many Oecobiids point forward then curve backwards; somehow in a running spider this gives a curiously scurrying, wheel-like impression that is characteristic of many Oecobiidae, and is helpful as a rough-and-ready aid to identification in the field. Characteristic of the family is the anal gland; it bears a tuft of long hairs. Typical colour patterns range from dark-patterned cream in some smaller species, to a small number of symmetrically-placed, conspicuous round light spots (commonly yellow or white) on a background that may be anything from a dull orange colour to black. The carapace is rounded and bears a compact group of six to eight eyes medially situated near the front of its dorsal surface.Many Oecobiidae build small, temporary star-shaped webs on or under rocks, or on walls or gravel. They hide near or below such webs and prey largely on ants, giving rise to common names such as "anteater" or "miervreter" (Afrikaans for anteater). Some of the Oecobiidae build tiny webs close to the ceilings in people's homes, which might have something to do with the family name (Oeco biidae meaning in essence "those who are house-living").

The species Oecobius navus occurs around the world.

While the genus Oecobius is cribellate, the genus Uroctea is ecribellate.

Persiculinae

Persiculinae is a taxonomic subfamily of minute to small predatory sea snails, marine gastropod mollusks. This subfamily includes several species which are micromollusks.

The subfamily is sometimes placed in the family Cystiscidae, and is sometimes instead left in the family Marginellidae the margin snails. It is within the clade Neogastropoda.

(Note: Gastropod taxonomy has been in flux for more than half a century, and this is especially true currently, because of new research in molecular phylogeny. Because of all the ongoing changes, different reliable sources can yield very different classifications.)

Prostatic acid phosphatase

Prostatic acid phosphatase (PAP), also prostatic specific acid phosphatase (PSAP), is an enzyme produced by the prostate. It may be found in increased amounts in men who have prostate cancer or other diseases.

The highest levels of acid phosphatase are found in metastasized prostate cancer. Diseases of the bone, such as Paget's disease or hyperparathyroidism, diseases of blood cells, such as sickle-cell disease or multiple myeloma or lysosomal storage diseases, such as Gaucher's disease, will show moderately increased levels.

Certain medications can cause temporary increases or decreases in acid phosphatase levels. Manipulation of the prostate gland through massage, biopsy or rectal exam before a test may increase the level.

Its physiological function may be associated with the liquefaction process of semen.

Selous's mongoose

Selous's mongoose (Paracynictis selousi) is a carnivore of southern Africa. It is the only member of the genus Paracynictis in the mongoose family.

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