Anal and rectal conditions

Question 1

How can you reduce the infection risk when operating on the anus or rectum?

Answer 1

• large clip
• evacuate rectum and place purse string or pack with swabs
• don’t use enemas
• pre-op i.v. antibiotics; e.g., cephalexin/metronidazole

Question 2

Which anal sphincter is important in faecal continence?

Answer 2

external - 50% of sphincter can be safely resected

Question 3

What are causes of anal sac disease?

Answer 3

Due to a change in consistency of secretion or interference with normal duct emptying; e.g., diarrhoea, diet, tapeworm, seborrhoea, oestrus, scar tissue
Remember neoplasia and bites in cats

Question 4

What are indications for anal sacculectomy? What are possible complications?

Answer 4

• Recurrent impaction
• Neoplasia
• On occasion, an additional component of the treatment for to perianal fistula (anal furunculosis)

Delay surgery if recently ruptured abscess

Complications
* draining sinus (some gland left)
* infection
* dehiscence
* tenesmus
* faecal incontinence

Question 5

Describe what anal furunculosis is. How is it treated? What are possible complications?

Answer 5

Perianal fistulae - suppurative, progressive, deep ulcerating tracts in the perianal tissues

Treatment
- cyclosporin for 12 weeks will resolve 60% but often recur (very expensive)
- hypoallergenic diet and immunosuppressive doseases of pred (only helped in 1/3 of mild cases)
- if there is anal sac involvement, dog will require anal sacculectomy

Complications
- cyclo can have adverse effects - v+/d+, coat changes, nephrotoxicity or hepatotoxicity, gingival hyperplasia

Question 6

Where are perianal adenomas most commonly found? How is it often treated?

Answer 6

• Hairless area of anal ring most common location, can see at tail base, prepuce and ventrum
• Normally seen in older patients
• Cats have no perianal glands

Treatment
- resolves with castration as testosterone dependent benign tumour

Question 7

Where are anal adenocarcinomas found? What clinical signs are associated? How are they treated?

Answer 7

Malignant lesion of perianal sebaceous glands
Can see dyschezia and pain

Treatment
* Do not respond to castration
* Aggressive surgical removal with adequate margins is indicated
* Adjunctive radiotherapy but rarely curative
* Regional lymph node excision
* Poor prognosis due to local recurrence and metastasis
* Distant metastasis can take many years to develop, repeat palliative local surgeries justified

Question 8

What change in electrolytes is seen with anal sac adenocarcinomas? What clinical signs are associated? How can the tumour be diagnosed? How can it be treated?

Answer 8

Paraneoplastic syndrome often accompanies
Tumour secretes PTH-like substance
Hypercalcaemia causes pu/pd, depression, weakness, weight loss

Diagnosis
* palpation
* biochemical findings
* Abdominal/thoracic radiographs
* abdominal/thoracic CT scans
* ultrasound of sublumbar lymph nodes

Treatment
- Treat hypercalaemia prior to surgery
* excision of primary mass
* Metastectomy
* adjunctive chemotherapy

Question 9

What are causes of perineal rupture? What animals are most likely to be affected? How can it be diagnosed? How is it usually treated? What are common complications?

Answer 9

• progressive weakening of pelvic diaphragm
• hormonal influence
• tenesmus
• congenital/acquired weakness
• colitis/prostatomegaly

Normally entire older male
Occasionally in bitch/cat

Diagnosis
* Reducible perineal swelling
* On rectal, absence of pelvic diaphragm
* Always check for bilateral disease
* Assess sphincter tone - chronic case can remain incontinent
* Ultrasound hernia/contrast urethrography will highlight bladder

Treatment
- cystocentesis through perineum if bladder is retroflexed
- herniorrhaphy
- colopexy
- castration

Complications
* Faecal incontinence
* suture placement
* duration of problem
* Urinary problems
* Infection
* Rectal prolapse
* Sciatic nerve entrapment
* Recurrence

Question 10

What can cause a rectal prolapse? How can it be treated?

Answer 10

Associated with endoparasites/enteritis in young animals and tumours or perineal hernias in middle aged/older animals
Recent straining; e.g., perineal surgery, constipation, urinary tract infection, dystocia, etc.

Treatment
* Ensure not intussusception
* Acute presentation
* lavage
* lubricate
* reduce and place purse string suture
* Non-reducible or severely traumatised
* amputation
* Recurrent
* colopexy

Question 11

What are rectal strictures often secondary to? What clinical signs are associated? How is it diagnosed? How is it treated?

Answer 11

Normally occur secondary to proctatitis chronic anal sacculitis, penetrating FB’s or as complication of anorectal sx

Clinically cause dyschezia, constipation and tenesmus

Diagnosis
* Diagnosed by digital rectal exam
* Contrast radiography/colonoscopy are difficult as superficially located
* Deep biopsy differentiates from neoplasia

Treatment
* Superficial strictures treated by bougienage (well lubricated finger/blunt instrument)
* This may need to be repeated at regular intervals for many days
* Corticosteroids then for 2-3 weeks
* Extensive strictures require resection by, for example, rectal pull-through

Question 12

What clinical signs are associated with rectal polyps? How are they treated?

Answer 12

Clinically
* blood/mucus in faeces
* tenesmus can occur
* polyp can occasionally prolapse from anus
* secondary rectal prolapse can occur
Treatment
* small pedunculated masses can be removed from distal rectum with electrocautery, or excision and suture placement
* larger polyps may need intestinal resection

Question 13

What structures are affected by rectal adenocarcinomas? What clinical signs are associated? How is it diagnosed? How are they treated?

Answer 13

Invades rectal wall causing fibrosis and stricture
Three sites
* colorectal junction and cranial 1/3 rectum
* middle 1/3 rectum
* caudal 1/3 rectum and anal canal

Clinically cause tenesmus, dyschezia, weight loss and lethargy with advanced malignancy

Diagnose on palpation, radiography, ultrasound, endoscopy/proctoscopy

Surgery
* colorectal resection and anastomosis +/- ischial pubic flap osteotomy
* dorsal perineal approach
* rectal pull-through
* consider and discuss continence with owners

Question 14

What is atresia ani? How is it diagnosed? How is it treated?

Answer 14

• Uncommon, can be associated with recto-vaginal or recto-urethral fistulae
• Secondary megacolon
• Neonate with absent anus
• Tenesmus and bulging of perineum
• Diagnosis confirmed by radiography
• Treatment involves creation of an anus by excision of skin and terminal rectal mucosa and careful suturing
• Subtotal colectomy (?)