SA Constipation Flashcards
(24 cards)
Constipation:
Infrequent or difficult fecal elimination
Obstipation:
Intractable constipation; Can cause impactions
Tenesmus:
Ineffectual and painful straining during defecation
Dyschezia:
Difficult or painful defecation that arises exclusively from disease of the anal and perianal tissues
Primary Function of the Large Intestine:
The Proximal Half absorbs water & electrolytes; The Distal Half provides storage for fecal material
Movement of intestinal contents occurs via 2 ways:
-Haustral Contractions: Allow for maximum absorption of H2O & Electrolytes; Slowly propels contents from cecum though ascending colon; And occur continuously throughout the day
-Mass movements moving material from the transverse colon to the rectum: Only a few occur per day (Especially after eating); Are conducted through the extrinsic nerves of the ANS
Normal Defecation:
-Stimulated by movement of feces into the rectum
-Continence is maintained by the internal (ANS) & external (Voluntary via Pudendal nerve) anal sphincters
-Peristaltic waves initiate defecation but will stop if the External Anal sphincter is not voluntarily relaxed
Extraintestinal Causes of Constipation:
-Inhibition of normal neural impulses of muscular function
-Interference with the Parasympathetic defecation reflex as a result of weakness, pain, or dyspnea
-Fecal consistency may be affected by dehydration or caused by mechanical obstruction due to compression of intestines
-Examples: Hypothyroid; Hypercalcemia; Hypokalemia; CRF; Myopathy; Thoracic cavity organs; Neuro. dz; Pelvic fractures
Intestinal and Anorectal causes of Constipation:
-Could be the result of an obstruction and/or the loss of motility
-May be caused by the inhibition of the defecation reflex due to pain
-Examples: Atresia ani; Perineal hernia; Prostatic disease; Perianal fistula
Signs of Constipation:
-Pain during defecation
-Arched back
-Vocalizing during defecation
-Stiff gait
-Reluctance to move
-Decreased fecal output
-Frequent attempts to defecate (Often unproductive)
Signalment:
-Cats: Most commonly megacolon!!!! Sacral Spinal deformities in Manx cats
-Intact Male Dogs: Prostatic dz; Perineal hernia
-Large Breed Dogs: Orthopedic dzs like hip dysplasia
-Very Young Dogs & Cats: Atresia ani
-German Shepherds: Higher risk of perianal fistulas
-Dysautonomia: Dogs from Kansas & Missouri; Cats from the UK
Physical Exam Findings:
-Visual inspection of perineal/anal area: Perianal fistulas, tumors, and atresia ani
-Digital rectal exam (!!!): Perineal hernia, masses, prostatic diseases, strictures, and pain
General Diagnostics:
-Baseline bloodwork & Urinalysis: Evaluate for extraintestinal causes and underlying disease
-Abdominal rads (May help to use contrast)
Abdominal US or CT if rads are unhelpful
-Colonoscopy if no apparent answer from other diagnostics
Diagnostics if No Fecal Production:
-Rectal Exam, Abd. Palpation, and Radiographs
-If colon is empty: Think inflammatory disease or a neurogenic disease
-If colon is full: It is Constipation or Obstipation
-Are Rectoanal diseases present: Perianal fistula; Perineal hernia; Neoplasia; Prostatic disease; Atresia ani
-If no Rectoanal disease is present: Megacolon or Metabolic disorders (Hypothyroidism, hypercalcemia, or hypokalemia)
Diagnostics if you have a small volume of feces and/or “ribbon-like stools:”
-Rectal Examination
-Radiographs
-Ultrasound if needed
-Colonoscopy if needed
-If luminal narrowing is detected: Neoplasia
-If there is Rectal & Anal stricture: Prostatomegaly; Pelvic Fractures
Atresia Ani:
-Most commonly reported congenital anorectal anomaly in dogs!!!
-4 Types
-May also have a rectovaginal or rectourethral fistula
-Clinical signs/Physical exams:
-Type 1: Normal until weaning, then constipation/tenesmus develops; May have stenosis at anal opening
-Types 2-4: Normal for first 2-4 weeks of age; Anorexia, abd. enlargement, restlessness, absent defecation; May develop vomiting and dehydration; Type 2/3 = imperforate anus + dimple where opening should be
-Diagnosis: Physical exam for exterior anal anomalies; Abd. rads
-Treatment: Type 1 = Balloon dilation or bougienage. Types 2 & 3 = Incision through skin at dimple; The rectum, from cranial to the end of blind pouch, is pulled caudally; Suture to skin
Atresia Ani Types:
-Type 1: Congenital stenosis of the anus without imperforate anus
-Type 2: Imperforate anus, distance to blind rectal pouch <1.5 cm
-Type 3: Imperforate anus, distance to blind rectal pouch >1.5 cm
-Type 4: Normal terminal rectal and anal development, cranial rectum ends as a blind pouch
Megacolon:
-Enlargement of the colon resulting in constipation and eventually obstipation
-Characterized by colonic hypomotility and a permanent increase in colonic diameter
-Most commonly occurs in cats!!!
-Split into 2 categories: Acquired & Idiopathic
-Diagnostics: Abd. rads (Colonic diameter >1.5x length of L7 vertebral body; Look for presence of pelvic fratures/stenosis); Bloodwork (Rule out systemic causes of neuromuscular dysfunction, thyroid panels, electrolytes)
-Idiopathic: Medical Management
-Acquired: Surgical Treatment
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 in manx cats, metabolic diseases [Hypothyroidism, hypokalemia])
Megacolon in Cats:
-Idiopathic in 62% of cases; 23% are due to previous pelvic fractures; 6% Neuro; 5% Manx (Sacral spinal abnormalities)
-Middle-aged male cats are most affected!!!
-Pathophysiology is poorly understood: Generalized dysfunction in long. and circular smooth muscle; Disturbance in activation of smooth muscle myofilaments
-Clin. Signs: Constipation or obstipation, fecal tenesmus; +/- abd. enlargement; +/- vomiting (May be due to vagal stimulation of CRTZ as a result of intestinal dilation); +/- paradoxical hernias (Liquid feces may pass around fecaliths)
-Physical Exam: Can palpate enlarged colon via abd. palpation; Digital rectal exam to rule out physical causes of obstruction; Full neuro. exam
Medical Management of Megacolon:
-For idiopathic Megacolons
-Removal of fecal material: Warm water or lactulose enemas; Deobstipation (Manual removal of feces under General Anesthesia); NO FLEET ENEMAS, they cause bad electrolyte derangements.
-IV/SQ fluids for dehydration
-Diet change (Royal canin fiber response diet)
-Laxatives: Lactulose, miralax, docusate, dulcolax
-Prokinetics: Cisapride
Surgical Treatment of Megacolons:
-Performed if med. management fails in idiopathic cases or if a megacolon is caused by old pelvic fractures with >6 months of constipation
-Subtotal Colectomy: Removal of the intra-abdominal portion of the colon; May also have to remove ileocecocolic junction to decrease tension on the anastomosis site
-If pelvic fractures present and <6 months of constipation: Can consider procedures to open the pelvic canal such as a pelvic osteotomy
Perineal hernias:
-Most common in intact, older male dogs
-Caused by weakness and separation of 3 pelvic diaphragm muscles: Coccygeus muscle; Levator ani muscle; and the Sphincter ani externus muscle
-Cause is likely multifactorial i.e: Hormonal imbalances, prostatic enlargements, a shortened or docked tail
-Clinical signs: Unilateral or bilateral perineal swelling; Constipation, tenesmus; Straining to urinate or urinary obstructions (This can be an emergency!!!!)
-Organs that can become entrapped are: Urinary bladder, prostate, and the small intestine
-Diagnostics: Digital Rectal Exam: Can palpate rectal sacculation due to weakness and disruption of muscular wall; Abd. Rads: Evaluate for prostatomegaly, determine what organs may be entrapped in hernia
-Medical Management: Laxatives, removal of fecal material from hernia if needed, and a urinary catheter if urinary obstruction is present
-Surgical treatment: Primary repair of the hernia (herniorrhaphy), castration is recommended, may recommend: cystopexy, colopexy, and vasopexy (for prostate).
Rectal Prolapse:
-Often secondary to GI parasites
-Most common in young cats & dogs
-Diagnosis made on physical exam
-Must differentiate from prolapsed intussuception: Place blunt instruments or finger between prolapse and anus (If can insert easily between them its intussusception; You should not be able to insert anything with a rectal prolapse)
-Treatment: Reduce prolapse (If tissue is viable). You should use lubrication and may need to apply items to decrease swelling such as 50% destrose or furosemide; Place pursestring suture that will allow fecal material to pass but not allow prolapse to recur (Leave in for 3-5 days); Treat underlying causes (Parasites, etc…); If prolapse recurs after pursestring then do a colopexy; If tissue is not viable or has been traumatized, do an R&A
