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)
What is the prognosis of a perineal hernia?
Good as long as there’s no tumor
Medical management- will likely recurr
What will you see in a partial rectal prolapse?
Just rectal mucosa, small, red rosette protruding from the anus
What will you see in a complete rectal prolapse?
Entire, rectal wall, red tube structure
What animals are usually seen presenting of rectal prolapse?
Young animals secondary to tenesmus associated with severe enteritis
How do you diagnose a rectal prolapse?
Inability to pass a probe between the rectal wall and prolapsed tissue
How do you treat a small rectal prolapse?
Gentle manual reduction with lubrication, deworm, low residue diet, stool softeners
How do you treat a large rectal prolapse?
Gentle manual replacement and placement of pursestring suture to tighten anal sphincter that can be left in 5-7 days
What is the prognosis of rectal prolapse?
First time: typically good
Recurrent or requiring surgery: guarded to poor
What is a rectal stricture?
Narrowing of rectal or anal lumen usually a consequence of neoplasia, severe inflammation, extraluminal compression, masses of bladder or LN
Usually in older animals
What are the clinical signs of rectal stricture?
Depends on severity of primary disease
Tenesmus, dyschezia, constipation or obstipation, hematochezia, ribbon stools
What will you find on a physical of an animal with a rectal stricture?
Palpate a narrow firm lumen, may be painful, may feel impacted stool proximally
What other diagnostics can you do for a rectal stricture and what will you find?
Radiographs: look for masses
Ultrasound: thickening of tissue, can do aspirates
Scoping: visualize and biopsy abnormal tissues
How do you treat rectal strictures?
Balloon dilation of stricture, treat primary disease, modify diet to soften stools
Surgery if required: mass removal or rectal pull through
Prognosis good for benign lesions
What sort of neoplasms are seen in the rectum?
Benign polyps most commonly
Differentials similar to colonic masses
What is atresia ani?
Congenital defect in puppies and kittens that is noteable within a few weeks of birth where there is an incomplete formation/opening of the anus
Males> females and poodles and bostons most commonly effected
What are the clinical signs of atresia ani?
Usually apparent once the animal starts consuming more solid foods
Tenesmus, absences of feces, no visible anal opening, perineal swelling or anal membrane protrusion due to accumulated feces
Rectovaginal/urethral fistula: watery or small amounts of stool, perivulvar erythema, bacterial cystitis and vaginitis
How do you diagnose atresia ani?
Clinical signs and physical exam
Imaging useful to determine extent of disease and surgical options
How do you treat atresia ani and what is the prognosis?
Surgery- technically demanding
Prognosis best for a simple persistant membrane, other types are fair to poor
What is a parianal fistula?
aka anal farunculosis
Chronic progressive inflammatory disease typically seen in middle aged to older dogs
GSDs irish setters and labs
What are the clinical signs of perianal fistulas?
Pain, dyschezia, fecal incontinence, hematochezia, over-grooming, self-mutilation
Pain may lead to lethargy, anorexia, and weight loss
What will you find on physical exam of a dog with perianal fistulas?
Perianal ulceration, foul smelling discharge, PAIN, may find stricture, assess anal glands
May need sedation or anesthesia to fully evaluate depending on pain level and extent of disease
What are the differentials for perianal fistulas?
Neoplasia, ruptured anal sac, trauma
What may be an etiology of perianal fistulas and what supports this?
Immune dysfunction supported by responsiveness to immune modulation medications
How do you treat perianal fistulas?
Deep cleaning of lesions (usually requires anesthesia) with continued at home cleanings, diet change, immune modulation therapy (predinsone or cyclosporine, topical tacrolimus)
Surgery may be required in cases of underlying anal sac pathology
What is the prognosis of perianal fistulas?
Guarded for cure but management is usually sucessful
Common complications: fecal incontinence, stricture, fisutla recurrence
What is typically a cause for euthanasia in a perianal fistula patient?
Quality of life issues
What are some causes of anal sac impaction?
Inflammation, impaction of glandular material, abscess
What are the clinical signs of anal sac impaction?
Excessive grooming, dyschezia, tenesmus, malodor, scooting/dragging hind end on the ground
T/F: You can diagnose anal sac impaction on a normal physical exam.
Only if severely impacted- abscess, erythema, protrusion of perineal area, draining tracts
More likely you’ll have to perform a recal exam
What is the findings in sacculitis?
Pain, granular, greenish yellow material, often hemorrhage
Associated with bacterial infection
What will the material in the anal sac look like if you have a true case of impaction?
Thick, foul smelling, grey-brown paste
What are the differentials for anal sac impactions?
Fistula, neoplasia, trauma
How do you treat anal sac impactions?
Gentle expression
Can flush with saline and try again if very thick material or plugged
How do you treat sacculitis?
Express material and flush the anal sac with saline of 0.5% chlorhex and instill with topical antibiotic
How do you treat an anal sac abscess?
Lance lesion (if not already ruptured), clip and clean area, systemic antibiotics
When would you consider anal saculectomy??
With recurrent or chronic issues that are becoming a quality of life or owner management issue
What is the prognosis of anal sac issues?
Usually very good
What is an anal sac apocrine gland adenocarcinoma?
Malignant, highly invsice and metastatic tumor mostly seen in dogs of the anal gland
What are the clinical signs of an apocrine gland carcinoma?
Tenesmus, constipation, anorexia, weight loss
Palpable firm nodule in or encompassing the anal sac often irregularly shaped
May be incidental
What are the diagnostic criteria for apocrine gland carcinoma?
Hypercalcemia, commonly lung mets, mass aspirates, surgical resection and histology of mass
How do you treat apocrine gland carcinomas and what is the prognosis?
Surgical resection, radiation, therapy
Prognosis is fair to guarded pending mets and hypercalcemia at time of diagnosis
Where do perianal adenomas arise from?
Circumanal glands
What dogs typically get perianal adenomas?
Usually seen in cockers, english bulldogs, samoyeds, beagles
Intact males predominate
What are the findings and clinical signs of perianal adenomas?
Usually solitary masses in perineal region, usually no CS, may see pain, obstruction, secondary infection, or pruritis
How do you tread perianal adenomas and what is the prognosis?
Surgical excision with castration
Prognosis is good but biopsy is recommended to confirm
What is fecal incontinence?
Loss of voluntary ability to retain feces or the involuntary passage of fecal material
What are the usual etiologies of fecal incontinence due to pathology?
Reservoir disease- stricture, fibrosis, or mural thickening, previous colonic sx
Sphincter disease- denervation or structual damage of rectum or anus
Which type of disease causing fecal incontinence usually leads to more severe clinical signs?
Sphincter disease since they are unaware that they NEED to defecate
T/F: Fecal incontinence can be seen in older/senior pets without any major underlying pathology.
True
How will your physical exam findings differ between fecal incontinence due to sphincter disease and reservoir disease?
Reservoir disease: usually no significant findings
Sphincter disease: anal sphincter tone diminished
How is fecal incontinence typically diagnosed?
History and physical exam findings
Look for underlying causes if nothing in history
How do you treat fecal incontenence?
Treat the primary disease
Change in diet and “bathroom” schedule, may need diapers and frequent cleaning
