Gastroenterology - Large Intestine Flashcards
Describe the structure of the large intestine
- lacks large villi
- invaginations of surface epithelium form intestinal crypts
- “Crypts of Leiberkuhn”
(goblet cells, endocrine cells, epithelial cells)
What are the functions of the large intestine?
- convert digested food waste into feces
- mucus and bicarbonate secretion
- resorb water, Na, and Cl
What are the typical clinical signs associated with colonic disease?
- diarrhea or constipation
- frank blood, mucus
- tenesmus, dyschezia
- urgency
- no weight loss or vomiting
What is “stress” colitis, and how is it treated?
- acute large bowel diarrhea
- often self-limiting
- tx: diet change, probiotic, fiber, Metro if severe
What is Trichuris vulpus?
What does it cause?
How is it transmitted?
- whipworm
- causes acute or chronic large bowel diarrhea
- fecal-oral contamination (egg ingestion)
What are the clinical signs of a Trichuris vulpus infection?
- can be asymptomatic
- hematochezia
- mucoid diarrhea
- tenesmus
How is Trichuris vulpus diagnosed?
- fecal float (eggs)
- ELISA
- colonoscopy in adults
How is Trichuris vulpus treated?
- Fenbendazole
- Preventatives
What is Heterobilharzia americana?
What does it cause?
- trematode/fluke
- “Schistosmiasis”
- acute or chronic large intestinal diarrhea
How is Heterobilharzia americana transmitted?
- reservoirs (small mammals)
- intermediate host (snails)
What is Tritrichomonas foetus?
What does it cause?
- protozoa that lives in descending colon and cecum
- chronic large intestinal diarrhea
What are the clinical signs of a Tritrichomonas foetus infection?
- large intestinal diarrhea
- tenesmus, fecal incontinence
- painful edematous rectum
How is Tritrichomonas foetus diagnosed?
- direct fecal smear
- PCR most sensitive
- fecal pouch culture
How is Tritrichomonas foetus treated?
- may be self-limiting
- Ronidazole
What is Prototheca?
- toxic algae found in soil and sewage
- blue-green algae bloom
What are the clinical signs of Prototheca infection?
Signs in dogs vs. cats?
- vomiting, diarrhea, ataxia, rapid death
- cats: cutaneous disease
- dogs: CNS, ocular, and large bowel signs
How is Prototheca diagnosed?
- culture
- rectal scraping
- biopsy
How is Prototheca treated?
Amphotericin B + Itraconazole
What is the prognosis for Prototheca infection?
- grave for disseminated dz
- guarded for cutaneous dz
What are the clinical signs of Campylobacter jejuni infection?
- acute or chronic colitis
- pyrexia
- anorexia
How is Campylobacter jejuni diagnosed?
- fecal culture
- direct fecal smear
(“seagull” shaped bacteria)
How is Campylobacter jejuni treated?
- none if healthy carrier
- Erythromycin and Tylosin
What is caused by Clostridium difficile?
toxin A - secretory diarrhea and tissue damage
toxin B - inflammation and necrosis of tissue
How is Clostridium difficle diagnosed?
- pin-shaped spores on fecal smear
- PCR and ELISA for toxins
- culture
How is Clostridium difficle treated?
Metronidazole
What are the clinical signs of primary large bowel enteropathy?
- large bowel diarrhea
- weight loss in advanced cases
What is fiber responsive colitis?
- chronic diarrhea without apparent pathogens, infection, inflammation, or neoplasia
- patient responds to high fiber diet
What are prebiotics?
- fibers fermented to short chain fatty acids
- energy source for healthy flora
What is inflammatory colonic disease?
chronic colitis for which no other cause is documented
- inflammatory infiltrates on histopathology
Which breeds are predisposed to Histiocytic Ulcerative Colitis?
- Boxers are #1
- French Bulldogs, Mastiffs, Malamutes, English Bulldogs
What are the clinical signs associated with histiocytic ulcerative colitis?
- tenesmus
- mucoid diarrhea
- hematochezia
- weight loss, decreased appetite
How is histiocytic ulcerative colitis diagnosed?
- ultrasound (thickened wall)
- histopathology (PAS positive macrophages)
- biopsy and culture
How is histiocytic ulcerative colitis treated?
- do not immune suppress
- Baytril
- stopping early will cause resistance
What are the most common neoplasms of the colon?
Adenocarcinoma and Lymphosarcoma
What is obstipation?
intractable constipation
- implies loss of some degree of function
- manual facilitated stool removal necessary
What are the causes of megacolon?
- constant constipation
- congenital dysfunction
- secondary to: colonic inertia or outlet obstruction
What are the clinical signs of megacolon?
- reduced, painful, or absent fecal production
- vomiting, decreased appetite
How is megacolon diagnosed?
- clinical path: dehydration, electrolyte imbalances
- radiographs
- colonoscopy/biopsy
How is megacolon treated?
- laxatives
- prokinetics
- diet modification
- enemas
- surgery
- removal of feces
What clinical signs may indicate pathology of the rectum?
- licking at hind end
- fecal incontinence
- discharge or smell
- tenesmus, dyschezia, hematochezia, constipation
What is proctitis?
What are the clinical signs?
inflammation of the rectal mucosa (secondary to other processes)
- tenesmus, dyschezia, hematochezia, excessive grooming
What is rectal stricture?
narrowing of rectal lumen +/- anal canal
- consequence of underlying disease
- see ribbon stools
How are renal strictures treated?
- Balloon dilation
- treat primary disease
- diet change, fiber, stool softeners
- surgery: rectal pull through, mass removal
What are the types of atresia ani?
1) imperforate anus
2) rectum ends in blind sac around cranial aspect of pelvis
3) rectal atresia
4) rectovaginal fistula with patent anus
What is anal farunculosis?
What are the clinical signs?
chronic, inflammatory disease
- dyschezia, fecal incontinence, hematochezia, excessive grooming, self-mutilation
What is found on physical exam with anal farunculosis?
- perianal ulceration
- foul smelling discharge
- pain
- possible stricture on rectal exam
How is anal farunculosis treated?
medical management more effective than surgery:
- topical meds, analgesics, antibiotics, diet change, immune modulation
What is the appearance of the anal sac secretions with anal sacculitis, and impaction?
sacculitis - granular, green-yellow, or hemorrhagic
impaction - thick, gray-brown paste
Treatments for:
- anal sac impaction
- sacculitis
- abscess
impaction - gentle expression of impacted gland
sacculitis - expression, flush with saline, topical antibiotics
abscess - lance, daily hygiene, systemic antibiotics
