anal membrane

a·nal mem·brane

the dorsal portion of the embryonic cloacal membrane is not divided by the urorectal septum as formerly thought; the term anal membrane is thus a misnomer.

anal membrane

See cloacal membrane.

anal

relating to the anus.

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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.

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.