Constipation Flashcards
define constipation, obstipation, tenesmus, dyschezia
constipation: infrequent or difficult fecal elimination
obstipation: intractable constipation
-inability to evacuate feces, can result in impaction
tenesmus: ineffectual or painful straining at defecation
dyschezia: difficult or painful defecation that arises exclusively from disease of the anal and perianal tissues
describe the primary functions of the large intestine
proximal half: absorb water and electrolytes
distal half: storage of fecal material
how do contents move through the large intestine?
- haustral contractions serve to mix the contents in the LI
-allows for maximal absorption of water and electrolytes
-slowly propel contents from cecum through ascending colon
-occur continuously throughout the day - mass movements move material from transverse colon to rectum
-only a few occur per day, esp after eating
-conducted through extrinsic nerves of ANS
describe defecation
- stimulated by movement of feces into the rectum
- continence maintained by internal and external anal sphincters
-ANS: internal
-voluntary control via pudendal nerve: external
3, peristaltic waves initiate defecation but will stop if voluntary relaxation of the external anal sphincter does not occur
describe extraintestinal causes of constipation
- may inhibit normal neural impulses or muscular function
- can interfere with the parasympathetic defecation reflex due to weakness, pain, or dyspnea
- may affect fecal consistency due to dehydration or cause mechanical obstruction due to compression
- examples:
-hypothyroidism
-hypercalcemia
-hypokalemia
-chronic renal failure
-myopathies
-thoracic cavity disease
-neurologic disease
-pelvic fractures
describe intestinal and anorectal diseases causing constipation
- obstruction
- inhibition of the defecation reflex because of pain
- loss of motility
- examples:
-atresia ani
-perineal hernia
-prostatic disease
-perianal fistula
describe specific history questions for constipation
- is the patient straining to defecate?
-NEED to see this to know it is constipation - when was the last time the patient defecated?
- how did the feces appear (color, ribbon-like, soft vs hard, etc.)
- any known history of trauma (recent or chronic) or recent surgery?
- any known concurrent diseases?
- any ingestion of indigestible material? (bone, hair, plastic, sticks, etc.)
what are the signs of constipation?
- pain during defecation
- arching back
- vocalization during defecation
- stiff gait
- reluctance to move
- decreased fecal output
- frequent attempts to have a bowel movement
describe how signalment can help narrow differentials down for constipation
- cats:
-most commonly idiopathic megacolon!!!!!
-or sacral spinal deformities in manx cats - intact male dogs:
-prostatic disease
-perineal hernia - large breed dogs:
-orthopedic diseases such as hip dysplasia - young dogs and cats:
-atresia ani - german shepherd: higher risk for perianal fistulas
- dysautonomia:
-dogs from Kansas and Missouri, cats from the UK
describe physical exam for constipation
- visual inspection of perineal/anal area:
-perianal fistula
-tumors
-atresia ani - digital rectal exam: should ALWAYS perform
-perineal hernia
-masses
-prostatic disease
-stricture
-pain
describe diagnostics for constipation
- baseline bloodwork and urinalysis
-CBC, biochem, panel
-eval for extraintestinal causes and underlying disease - abdominal radiographs:
-contrast may be beneficial - abdominal ultrasound or CT
- colonoscopy if no apparent answer on other diagnostics
describe the diagnostic tree for constipation
- present with no fecal production: rectal exam, abd palpation, radiographs
- if colon is full:
-constipation or obstipation, so check for rectoanal disease
-if rectoanal disease present: perianal fistula, perineal hernia, neoplasia, prostatic disease, atresia ani
-if no rectoanal disease: megacolon, metabolic disorders (hypothyroid, hypercalcemia, hypokalemia)
- if colon is empty:
-inflammatory disease
-neurogenic disease: dysautonomia - if presented with small volume feces or ribbon-like stools:
-rectal exam, rads, US, colonoscopy
-luminal narrowing, neoplasia, rectal and anal stricture, prostatomegaly, pelvic fractures
describe atresia ani
- most commonly reported congenital anorectal anomaly in dogs
- 4 types:
-type 1: congenital stenosis of the anus without imperforate anus
-type 2: imperforate anus (just a dimple), distance to blind rectal pouch <1.5cm
-type 3: imperforate anus, distance to blind rectal pouch >1.5cm
-type 4: normal terminal rectal and anal development but cranial rectum ends as a blind pouch
- may also have rectovaginal or rectourethral fistula
-not completely obstructed, but pooping out vulva or urethral = still very wrong
describe clinical signs/physical exam of atresia ani
type 1:
-normal until weaning, then constipation/tenesmus
-may have stenosis at anal opening
type 2-4:
-normal for 1st 2-4 weeks
-anorexia, abdominal enlargement, restless
-absent defecation
-may develop vomiting and dehydration
-type 2 and 3 have imperforate anus and dimple where opening should be
describe diagnosis and treatment of atresia ani
diagnosis:
1. PE for exterior anal anomalies (rectal if you can but usually puppies so not super possible)
2. abd radiographs
treatment:
-type 1: balloon dilation or bougienage
-type 2 and 3:
–incision through skin at dimple
–rectum from cranial to the end of blind pouch pulled caudally
–sutured to skin
describe megacolon
- enlargement of colon leading to constipation and eventually obstipation
- characterized by colonic hypomotility and a permanent increase in colonic diameter
- most commonly occur in cats
-can occur in dogs more rarely - 2 categories: acquired and idiopathic
describe acquired megacolon
- mechanical causes:
-extraluminal compression: pelvic fractures, prostatomegaly, pelvic masses
-intraluminal compression: intraluminal stricture, neoplasia, FB
- functional causes:
-neuromuscular dysfunction: spinal cord disease, dysautonomia, pelvic nerve injury, sacral spinal abnormalities (manx cats)
-metabolic disease: hypothyroid, hypokalemia
describe megacolon in cats
- idiopathic in 62%
-23% pelvic fractures
-6% neuro dysfunction
-5% manx - middle aged, male cats most affected
- pathophysiology poorly understood
-generalized dysfunction in longitudinal and circular smooth muscle
-disturbance in activation of smooth muscle myofilaments
describe clinical signs of megacolon in cats
- constipation or obstipation
- fecal tenesmus
- +/- abd enlargement
- +/- vomiting:
-may be due to vagal stimulation of CRTZ from intestinal dilation - +/- paradoxical diarrhea: liquid feces may pass around fecoliths
describe PE for megacolon in cats
- can palpate enlarged colon via abdominal palpation
- digital rectal exam:
-rule out physical causes of obstruction (atresia ani, pelvic stenosis, prostatomegaly, masses) - full neuro exam to eval for any muscular weakness or spinal cord dysfunction
describe diagnostics of megacolon in cats
- abd rads:
-colonic diameter >1.5x length of L7 vertebral body on lateral projection
-eval for evidence of pelvic fractures/pelvic stenosis - bloodwork:
-rule out systemic causes of neuromuscular dysfunction
-thyroid panel, electrolytes
describe medical treatment of megacolon in cats
- medical management for idiopathic
-removal of fecal material:
–warm water or lactulose enemas: mild cases
–deobstipation (more severe): manual removal of feces under general anesthesia
-NO fleet enemas!! - IV/SQ fluids to correct dehydration
- diet change: royal canine fibre response diet
- laxative: lactulose, miralax, docusate, dolculax
- prokinetic: cisapride
describe surgical treatment of megacolon in cats
- performed if medical management fails in idiopathic or if caused by old pelvic fractures with >6 months of constipation
- subtotal colectomy:
-removal of intra-abdominal portion of the colon
-may also have to remove the ileocecocolic junction to decrease tension on the anastomosis site - if pelvic fractures and less than 6 months of constipation
-can consider procedures to open pelvic canal such as pelvic osteotomy
describe perineal hernias
- most common in intact older male dogs
-SHOULD tell owners who choose not to castrate - caused by weakness and separation of pelvic diaphragm
- likely multifactorial cause:
-hormonal imbalance
-prostatic enlargement
-short or docked tail
describe clinical signs of perineal hernia
- uni or bilateral perineal swelling
- constipation
- tenesmus
- straining to urinate or urinary obstruction: can be an emergency
- organs that can become entrapped: urinary bladder, prostate, small intestine
describe diagnosis of perineal hernias
- digital rectal exam: can palpate rectal sacculation due to weakness and disruption of muscular wall
-go in and point finger back at you = very wrong - abdominal radiographs (including hernia) recommended:
-eval for prostatomegaly
-determine what organs may be entrapped in hernia
describe treatment of perineal hernia
- medical management:
-laxatives: lactulose
-removal of fecal material from hernia if needed
-urinary catheter if urinary obstruction - surgical treatment:
-primary repair of hernia: herniorraphy
-may recommend cystopexy, colopexy, vasopexy
-castration recommended
describe rectal prolapse
- often secondary to GI parasites
- most common in young cats and dogs
- diagnosis:
-PE
-must differentiate from prolapsed intussusception!
–blunt instrument or finger between prolapse and anus: if can insert easily between them = intussusception
–should NOT be able to insert anything with rectal prolapse
describe treatment of rectal prolapse
- reduce prolapse if tissue viable
-apply lube; may need to apply 50% dextrose or furosemide to reduce swelling first - place pursestring suture that will allow fecal material to pass but not allow the prolapse to recur
-leave for 3-5 days - treat underlying cause in the meantime
- if prolapse occurs after pursestring, colopexy may be necessary
- if tissue is not viable or has been traumatized: R&A may be necessary
