anal fold

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anal fold

a slight elevation flanking the cloacal membrane and derived from a cloacal fold; anal folds form the border of the anus.


relating to the anus.

anal abscess
acute, purulent infections in the area of the anus, usually caused by gram-negative organisms. In dogs, these most often arise from the anal sacs.
anal atresia, atresia ani
congenital absence or stenosis of the anus manifested by an absence of feces and a gradual development of abdominal distention. Fistulae may develop between the rectum and urogenital tract. The anomalous development can occur in several forms and may be accompanied by similar atresia at higher levels of the intestine. There is usually normal development of sphincters. A dimple is usually evident at the point at which surgical intervention is required.
anal canal
the short, terminal, retroperitoneal segment of the intestinal tract between the rectum and anus.
anal constriction
a congenital constriction combined with vulvar constriction occurs in Jersey cattle.
anal fibroma
occurs in cattle and excision effected for esthetic reasons.
anal fistula
see perianal fistula.
anal fold
see anal fold.
anal furunculosis
see perianal fistula.
anal membrane
the dorsal part of the cloacal membrane in the embryo; when it eventually breaks down the dorsal passage becomes the rectoanal passage.
anal-perineal laceration
see rectovaginal fistula.
anal prolapse
the protrusion of a small amount of mucosa through the anus.
anal reflex
the pursing of the anal orifice when the perineum is stimulated; indicative of an animal with intact sacral segments of the spinal cord.
anal sac
see anal sacs.
Enlarge picture
Anal sacs in the dog. By permission from McCurnin D, Poffenbarger EM, Small Animal Physical Diagnosis and Clinical Procedures, Saunders, 1991
anal sacculitis
inflammation of the anal sacs.
anal sphincter
the internal anal sphincter is formed from smooth muscle of the anal canal while the external anal sphincter, which is larger and of greater importance in fecal continence, consists of striated muscle.
anal sphincter hypertrophy
occurs in aged dogs and may give rise to difficult and painful defecation.
anal stenosis
scar formation after perianal fistulae, trauma, severe anal sac disease, or treatment for neoplasia may result in a reduced lumen and particularly a loss of the capacity to dilate with passage of feces. Straining, passage of ribbon-like feces and constipation result.
anal ulceration
inflammation and ulceration of the perianal skin which may be associated with anal sac disease. Seen most commonly in German shepherd dogs.