Anal glands
Encyclopedia
The anal glands or anal sacs are small glands found near the anus in many mammal
s, including dogs and cats. They are not found in humans or other primates. They are paired sacs located on either side of the anus between the external
and internal sphincter muscles
. Sebaceous gland
s within the lining secrete a liquid that is used for identification of members within a species. These sacs are found in all carnivora
except bear
s and sea otter
s. The liquid produced usually smells foul to humans.
s, these glands are occasionally referred to as "scent glands", because they enable the animals to mark their territory and identify other dogs. The glands 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 glands usually empty when the dog defecates, lubricating the anal opening in the process. 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 gland pushes on the anus. The glands can be emptied by the dog's keeper, or more typically by a groomer or veterinarian, by squeezing the gland so the contents are released through the small openings on either side of the anus. Discomfort is evidenced by the dog dragging its posterior on the ground, licking or biting at the anus, sitting uncomfortably, having difficulty sitting or standing, or chasing its tail.
Discomfort may also be evident with impaction or infection of the anal glands. Anal gland impaction results from blockage of the duct leading from the gland to the opening. The gland is usually nonpainful and swollen. Anal gland infection results in pain, swelling, and sometimes abscess
ation and fever. Treatment is by expression of the gland, lancing of an abscess, and oral antibiotic
s and antibiotic infusion into the gland in the case of infection. The most common bacteria
l isolates from anal gland infection are E. coli
, Enterococcus faecalis
, Clostridium perfringens
, and Proteus
species.
Anal glands 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 fistula
e.
Anal gland fluid is normally yellow to tan in color and watery in consistency. Impacted anal gland material is usually brown or gray and thick. The presence of blood or pus indicates infection.
s, these glands may become impacted, causing the cat to defecate outside the litter box, almost anywhere in the house. The veterinarian can empty the clogged glands, and defecating outside the litter box will stop immediately in most cases. Too often this problem is incorrectly interpreted as behavioral, when it is entirely a problem of clogged or blocked anal glands or difficulty defecating.
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.
s use their anal glands to spray a foul-smelling and sticky fluid as a defense against predators.
Mammal
Mammals are members of a class of air-breathing vertebrate animals characterised by the possession of endothermy, hair, three middle ear bones, and mammary glands functional in mothers with young...
s, including dogs and cats. They are not found in humans or other primates. They are paired sacs located on either side of the anus between the external
Sphincter ani externus muscle
The Sphincter ani externus is a flat plane of muscular fibers, elliptical in shape and intimately adherent to the integument surrounding the margin of the anus.-Anatomy:...
and internal sphincter muscles
Sphincter ani internus muscle
The Sphincter ani internus is a muscular ring that surrounds about 2.5 cm of the anal canal; its inferior border is in contact with, but quite separate from, the Sphincter ani externus....
. Sebaceous gland
Sebaceous gland
The sebaceous glands are microscopic glands in the skin that secrete an oily/waxy matter, called sebum, to lubricate and waterproof the skin and hair of mammals...
s within the lining secrete a liquid that is used for identification of members within a species. These sacs are found in all carnivora
Carnivora
The diverse order Carnivora |Latin]] carō "flesh", + vorāre "to devour") includes over 260 species of placental mammals. Its members are formally referred to as carnivorans, while the word "carnivore" can refer to any meat-eating animal...
except bear
Bear
Bears are mammals of the family Ursidae. Bears are classified as caniforms, or doglike carnivorans, with the pinnipeds being their closest living relatives. Although there are only eight living species of bear, they are widespread, appearing in a wide variety of habitats throughout the Northern...
s and sea otter
Sea Otter
The sea otter is a marine mammal native to the coasts of the northern and eastern North Pacific Ocean. Adult sea otters typically weigh between 14 and 45 kg , making them the heaviest members of the weasel family, but among the smallest marine mammals...
s. The liquid produced usually smells foul to humans.
Dogs
In dogDog
The domestic dog is a domesticated form of the gray wolf, a member of the Canidae family of the order Carnivora. The term is used for both feral and pet varieties. The dog may have been the first animal to be domesticated, and has been the most widely kept working, hunting, and companion animal in...
s, these glands are occasionally referred to as "scent glands", because they enable the animals to mark their territory and identify other dogs. The glands 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 glands usually empty when the dog defecates, lubricating the anal opening in the process. 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 gland pushes on the anus. The glands can be emptied by the dog's keeper, or more typically by a groomer or veterinarian, by squeezing the gland so the contents are released through the small openings on either side of the anus. Discomfort is evidenced by the dog dragging its posterior on the ground, licking or biting at the anus, sitting uncomfortably, having difficulty sitting or standing, or chasing its tail.
Discomfort may also be evident with impaction or infection of the anal glands. Anal gland impaction results from blockage of the duct leading from the gland to the opening. The gland is usually nonpainful and swollen. Anal gland infection results in pain, swelling, and sometimes abscess
Abscess
An abscess is a collection of pus that has accumulated in a cavity formed by the tissue in which the pus resides due to an infectious process or other foreign materials...
ation and fever. Treatment is by expression of the gland, lancing of an abscess, and oral antibiotic
Antibiotic
An antibacterial is a compound or substance that kills or slows down the growth of bacteria.The term is often used synonymously with the term antibiotic; today, however, with increased knowledge of the causative agents of various infectious diseases, antibiotic has come to denote a broader range of...
s and antibiotic infusion into the gland in the case of infection. The most common bacteria
Bacteria
Bacteria are a large domain of prokaryotic microorganisms. Typically a few micrometres in length, bacteria have a wide range of shapes, ranging from spheres to rods and spirals...
l isolates from anal gland infection are E. coli
Escherichia coli
Escherichia coli is a Gram-negative, rod-shaped bacterium that is commonly found in the lower intestine of warm-blooded organisms . Most E. coli strains are harmless, but some serotypes can cause serious food poisoning in humans, and are occasionally responsible for product recalls...
, Enterococcus faecalis
Enterococcus faecalis
Enterococcus faecalis – formerly classified as part of the Group D Streptococcus system – is a Gram-positive, commensal bacterium inhabiting the gastrointestinal tracts of humans and other mammals. It is among the main constituents of some probiotic food supplements. Like other species in the genus...
, Clostridium perfringens
Clostridium perfringens
Clostridium perfringens is a Gram-positive, rod-shaped, anaerobic, spore-forming bacterium of the genus Clostridium. C. perfringens is ever present in nature and can be found as a normal component of decaying vegetation, marine sediment, the intestinal tract of humans and other vertebrates,...
, and Proteus
Proteus (bacterium)
Proteus is a genus of Gram-negative Proteobacteria.-Clinical significance:Three species—P. vulgaris, P. mirabilis, and P. penneri—are opportunistic human pathogens. Proteus includes pathogens responsible for many human urinary tract infections. P. mirabilis causes wound and urinary...
species.
Anal glands 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
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. At least one case has been reported in a cat...
, a malignant tumor. Potential complications include fecal incontinence (especially when both glands are removed), tenesmus
Tenesmus
Rectal tenesmus is a feeling of incomplete defecation. It is experienced as an inability or difficulty to empty the bowel at defecation...
from stricture or scar formation, and persistent draining fistula
Fistula
In medicine, a fistula is an abnormal connection or passageway between two epithelium-lined organs or vessels that normally do not connect. It is generally a disease condition, but a fistula may be surgically created for therapeutic reasons.-Locations:Fistulas can develop in various parts of the...
e.
Anal gland fluid is normally yellow to tan in color and watery in consistency. Impacted anal gland material is usually brown or gray and thick. The presence of blood or pus indicates infection.
Cats
In catCat
The cat , also known as the domestic cat or housecat to distinguish it from other felids and felines, is a small, usually furry, domesticated, carnivorous mammal that is valued by humans for its companionship and for its ability to hunt vermin and household pests...
s, these glands may become impacted, causing the cat to defecate outside the litter box, almost anywhere in the house. The veterinarian can empty the clogged glands, and defecating outside the litter box will stop immediately in most cases. Too often this problem is incorrectly interpreted as behavioral, when it is entirely a problem of clogged or blocked anal glands or difficulty defecating.
Opossums
OpossumsDidelphimorphia
Opossums make up the largest order of marsupials in the Western Hemisphere, including 103 or more species in 19 genera. They are also commonly called possums, though that term technically refers to Australian fauna of the suborder Phalangeriformes. The Virginia opossum was the first animal to be...
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
SkunkSkunk
Skunks are mammals best known for their ability to secrete a liquid with a strong, foul odor. General appearance varies from species to species, from black-and-white to brown or cream colored. Skunks belong to the family Mephitidae and to the order Carnivora...
s use their anal glands to spray a foul-smelling and sticky fluid as a defense against predators.