Anal glands, also known as anal sacs, are small glands located near the anus in many mammals.
Positioned between the external and internal anal sphincter muscles.
In non-human mammals, these glands secrete volatile organic compounds for communication (territory marking, identification, sexual signaling, defense).
Function in humans is unclear.
Secretions and Species
Sebaceous glands secrete a liquid for species identification.
Common among carnivorans like wolves, bears, sea otters, and kinkajous.
Human anal glands average 12 per person, located within the anal canal wall.
Function in Humans
Secretions contain mucin, differing from rectal mucosa.
Specific function in humans remains unclear.
Clinical Significance
Anal glands are often the cause of anal fistulas.
Cryptoglandular theory: duct obstruction by foreign material can cause abscess and fistula.
Infections can result from bacterial entry, causing abscesses and inflammation.
Animals and Anal Gland Use
Dogs and cats use anal gland secretions for territory marking.
Secretions are released during defecation, or when anxious/frightened.
Fluid appearance and odor vary among individuals.
Inability to express can lead to anal sacculitis (painful condition).
Treatments include manual expression, antibiotics, or surgery (sacculectomy).
Notable bacteria: E. coli, Enterococcus, Clostridium perfringens, Proteus.
Other Mammals
Opossums use glands for defense by mimicking death and secreting foul odors.
Skunks spray a foul-smelling fluid as a defense.
Symbiotic Relationships
Beavers have castor sacs and anal glands for scent communication.
Castoreum secreted for perfumery and flavoring.
Bacterial flora includes B. fragilis and E. coli.
European Badgers use VOCs in AGS for communication, indicating reproductive status and group membership.
Hyenas use pasting behavior for scent marking.
Microbiome differs by sex and age, with common bacteria including Anaerococcus and Corynebacterium.
Bacteria in Dogs and Cats
Bacteria found in anal glands are also present in oral flora due to grooming behaviors.
Typical bacteria include Streptococci and Enterococci.
Notable Points
Anal sac adenocarcinoma: tumor leading to potential sacculectomy.
Hyena butter: secretion from hyena glands used for marking.
References
Provided references include various studies and textbooks related to the anatomy and function of anal glands in different species.