Rectum and Anus Flashcards
What parts of the anatomy comprise rectum and anus?
Rectum, anal canal, internal and external anal sphincters, muscles of pelvic diaphragm, perianal skin, subcutaneous tissues
What type of tissue makes up the rectal mucosa?
Columnar epithelium, lymphoid follicles, many mucous secreting goblet cells
What kind of tissue is at the rectal-anal junction?
Stratified squamous epithelium
What is the function of the rectum and anus?
Storage and evacuation of feces
What kind of muscle is in the internal and external spincters?
Internal- smooth muscle, involuntary
External- skeletal, voluntary
What do the muscles of the pelvic diaphragm diaphragm do?
- Provide structure and support of rectoanal canal
- Help with evacuation of feces and compression of rectum during defecation
What are the three types of glands within the anal canal?
- Anal glands
- Circumanal glands (hepatoid)
- Glands of the anal sac
What are the anal glands?
Modified sweat glands that secret lipids into the anal canal
What are circumanal glands?
Non-secretory
What are glands of the anal sac?
Contain protein, bacteria, sebaceous fluid, desquamated cells
- Scent gland
- Anal sac sit in between the inner and external muscle layers just inside anal sphincter
What provides parasympathetic supply to the anus and rectum?
Pelvic nerve- stimulate rectal motility and relaxes internal anal sphincter
Allows for defecation when relaxed
What provides sympathetic supply to the anus and rectum?
Hypogastric nerve from lumbar spine- inhibits rectal motility and causes contraction of internal sphincter
Retention of fecal material
What provides somatic supply to the anus and rectum?
Pudendal nerve- allows maximum distension of rectum for fecal storage and anal control
What other non-GI signs do you see in animals with hypogastic and pudendal nerve issues?
Dysuria or urinary incontinence
What are the two most common pathologies in the anus and rectum?
Neuromuscular and mucosal pathologies
T/F: Disease here is often fatal but doesn’t typically affect quality of life.
False- diseases are rarely fatal on their own but severely effect quality of life
What are the usual signs of disease of the rectum and anus?
- Licking at hind end
- Fecal incontinence
- Discharge or smell from anal region
- Some overlap with colonic disease (tenesmus, hematochezia, constipation)
T/F: Clinical signs associated with assimilation of nutrients or water are commonly seen with rectal and anal diseases.
False
What are common physical exam findings of rectal and anal disease?
Perineum: swelling, masses, fistulas, abscesses, herniation, prolapse
Rectal exam: anal sacs, anal tone, diameter, pelvic canal, smoothness of rectal surface, fecal content
Also palpate urethral, prostate, and assess region LNs
Often painful and may need to sedate
Are clin path tests really rewarding when assessing rectal and anal diseases?
No- usually used to exclude other issues
Coag profiles may be useful to assess ongoing bleeding
How do you test for pathogens?
Fecal floatation
Cultures or PCR
Giardia, cryptosporidium, tritrichomonas
What are the limitations of radiography and ultrasound?
Location of lesion may make interpretation difficult
Rigid proctoscopy may be more useful for assessing caudal lesions
What is the empiric treatment for acute disease?
Deworming, addition of fiber, diet change
What is proctitis?
Inflammation of the rectal mucosa secondary to foreign bodies, prolapse, or extension of colitis
What are the clinical signs of proctitis?
Tenesmus, dyschezia, hematochezia
What do you have to exclude when assessing proctitis?
FB, infection, neoplasia
If these are excluded perform biopsy to find inflammatory infiltrates
What is the treatment of proctitis identical to?
Colitis
What is a perineal hernia?
Protrusion of rectal wall and other pelvic/abdominal organs through a weakened portion of the pelvic diaphragm into the ischiorectal fossa
What are the organs commonly involved in a perineal hernia?
Bladder, prostate, omentum, SI, descending colon
Less common in cats
What are the most common muscles that fail to result in a perineal hernia?
Levator ani, coccygeal, internal and external anal sphincter mucles, and fascia
What are the clinical signs of a perineal hernia?
Perianal swelling, tenesmus, dyschezia, possible dysuria and stranguria
With concurrent disease: constipation, masses, anal sac lesion, prostatomegaly, anything tenesmus causing
What animals are the most likely to get perineal hernias?
Middle aged intact male dogs
Suggests hormonal component
T/F: Many animals will live free of clinical signs of a perineal hernia for many years.
True- often causes to major issues
How do you treat perineal hernias?
- Attempt gentle manual reduction
- Emergency if they cannot urinate
- Surgery (herniorrhaphy to reappose muscles)