Anal gland
The anal glands or anal sacs are small glands found near the anus in many mammals, including dogs and cats. They are paired sacs located 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 all carnivora except bears,[1] sea otters[2] and kinkajous.[3] The liquid produced usually smells foul to humans.
Contents |
[edit] Dogs
In dogs, 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. 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 abscessation and fever. Treatment is by expression of the gland, lancing of an abscess, and oral antibiotics and 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.[4]
Both dogs and cats have anal sacs that may become impacted or infected if not emptying properly. This causes itching, scooting, bad odor and sometimes pain, too. Severe cases may abscess and rupture. Learn the signs of anal sac problems and how to keep your pet comfortable and scoot-free. A pet "scooting", or dragging the hind end on the carpet, grass, or your favorite rug is something many people have witnessed at one time or another. More common in mid- to smaller-sized dogs, but occasionally seen in larger dogs or cats. Scooting is also common in overweight pets. Most often is it because their anal sacs are bothering them. Anal sacs should empty regularly (and unnoticed) with normal bowel movements. If they don't, they may become impacted, infected (abscess) and possibly rupture. There are other possible causes for scooting or anal discomfort: a perianal tumor that is infected or bothersome, irritation from diarrhea, parasites, matted hair. A scooting pet should be examined by your vet to rule out these potential problems. Most often, it is an inflammation, infection, or impaction of the anal sacs. Anal sacs collect the oily secretion of the glandular tissue that lines the sacs (also called Anal Glands). The sacs are located between the external and internal muscular rings of the anus. Viewed from behind, the sacs would sit at approximately the 8 o'clock and 4 o'clock positions, below the anus.
Normally a bowel movement is sufficient to express the sacs. However, if the animal is sick, i.e. with loose stool or diarrhea, the sacs to not get emptied as they normally would. Dietary changes that cause a temporarily looser stool than normal can also be a cause. Animals that are overweight have less muscle tone and sometimes additional fat tissue in the way of proper emptying of the sacs. Skin infections and seborrhea may delay sac emptying as well. The first thing to do is to make an appointment with your vet. Ruling out other potential causes for scooting is the first step. Some animals may get the anal sacs emptied by scooting, grooming themselves, etc., but left untreated, a simple irritation can lead to infection, impaction, and ultimately abscessation and rupture! Better safe than sorry. Anal sac infections are very painful for the pet, and more difficult/uncomfortable/expensive to treat in later stages.
There are basically two methods -- external and internal anal sac expression. External expression is accomplished pushing gently on the skin over the sacs in an upward motion toward the anus, to empty the contents of the sacs (make sure to have a tissue at the ready!) Internal expression requires a latex glove and inserting an index finger just inside the anal sphincter to aid in pushing out the contents of the sac with thumb pushing on the outside of the sac. The pet should be properly restrained to avoid injury to the pet and the person. It is best to have your veterinarian to show you the proper technique for safe restraint and proper anal sac emptying. In the best case, this is not necessary: they should take care of themselves. However, some pets have recurrent problems with anal sacs not emptying properly. Routine emptying when not necessary is not recommended - the expression may disturb the normal balance, leading to inflammation or infection.
Keeping your pet at an optimal weight will help. Some pets are also helped by adding some fiber to the diet to help bulk up the stools. Your veterinarian will be able to help you with available options for diet, too.[5] 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 fistulae.[6]
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.
[edit] Cats
In cats, 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.
[edit] 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.
[edit] Skunks
Skunks use their anal glands to spray a foul-smelling and sticky fluid as a defense against predators.
[edit] Weasels
Research by the Institute for Pheromone Research and the Department of Chemistry, Indiana University suggests that weasels may use their anal glands in gender recognition.[7]
[edit] See also
[edit] References
- ^ Dyce, K.M.; Sack, W.O.; Wensing, C.J.G. (1987). Textbook of Veterinary Anatomy. W.B. Saunders Company. ISBN 0-7216-1332-2.
- ^ Kenyon, Karl W. (1969). The Sea Otter in the Eastern Pacific Ocean. Washington, D.C.: U.S. Bureau of Sport Fisheries and Wildlife.
- ^ Ford, L. S.; Hoffman, R. S. (1988-12-27). "Potos flavus". Mammalian Species (American Society of Mammalogists) 321: 1-9. JSTOR 3504086. http://www.jstor.org/stable/10.2307/3504086. Retrieved 2012-01-30.
- ^ Ettinger, Stephen J.;Feldman, Edward C. (1995). Textbook of Veterinary Internal Medicine (4th ed.). W.B. Saunders Company. ISBN 0-7216-6795-3.
- ^ Tobiassen Crosby, DVM, Janet. "Why does my pet scoot?". The New York Times Company. http://vetmedicine.about.com/od/veterinaryqa/a/Anal-Sacs-and-Scooting.htm. Retrieved 30 January 2012.
- ^ 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. http://avmajournals.avma.org/doi/abs/10.2460/javma.2002.221.662.
- ^ Zhang JX, Soini HA, Bruce KE, et al. (November 2005). "Putative chemosignals of the ferret (Mustela furo) associated with individual and gender recognition". Chem. Senses 30 (9): 727–37. doi:10.1093/chemse/bji065. PMID 16221798. http://chemse.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=16221798.
Zhang JX, Ni J, Ren XJ, Sun L, Zhang ZB, Wang ZW (June 2003). "Possible coding for recognition of sexes, individuals and species in anal gland volatiles of Mustela eversmanni and M. sibirica". Chem. Senses 28 (5): 381–8. doi:10.1093/chemse/28.5.381. PMID 12826534. http://chemse.oxfordjournals.org/cgi/pmidlookup?view=long&pmid=12826534.
