Surgical approach to the LI in small animals Flashcards by Emily Stacey

2 surgical approaches for colorectal surgery

ventral midline laparotomy
pelvic split
transanal

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Which nerves pass through obturator foramen?

sciatic and obturator nn

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Define colotomy

Full thickness biopsy of the colon (same basic principles as enterotomy)

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How is LI resection and anastomosis different to that in the SI?

Same basic principles but biggest difference is the delayed healing time of the LI

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Risk if you remove too much colon = ?

Faecal incontinence (loss of reservoir and absorptive capacities)

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What happens if you disrupt ileocaecocolic junction?

Disruption of ileal function - normally this prevents retrograde flow of colonic backeria into SI to decrease risk of SIBO

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How much of a rectal resection causes faecal incontinence?

6cm or more

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How to anastomose LI ?

sutures or staples

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Describe the suture you’d use for LI anastomosis. Why? 4

Single laye rof simple interrupted appositional using a monofilament, PDS2 (loses 26% strength in 14 days). WHY? optimises wound healing, faster gain in tensile strength, minimise decrease in lumen diameter, decreased incidence of complications.

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How is a stapler used?

Inserted via an incision in th ecaecum or via the anus.

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How does an end-to-end anastomosis stapler work?

causes an inverted anastomosis (i.e. there is some inversion of wound (makes the risk of stricture slightly higher). Causes a little post-op bleeding from rectum.

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Complications of colorectal surgery 7

dehiscence –> septic peritonitis
wound infection
abscess
faecal incontinence
stricture and tenesmus
rectal prolapse
haematoxhezia

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Name 3 surgical diseases of colon and rectum

Megacolon, neoplasia, rectal prolapse

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Causes of megacolon - 2 (examples)

PRIMARY/IDIOPATHIC - cats
SECONDARY - pelvic fractures, intrapelvic SOL (neoplasia, lymphadenopahty, abscess), colorectal neoplasia, colorectal abscess, perineal hernia, inappropriate diet

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Diagnosis - megacolon

Signs (chronic constipation, tenesmus, vomiting, anorexia, weight loss)
Large colon containing faecal material, dehydration, poor BCS
rule out underlying cause for constipation

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Megacolon -treatment

MEDICAL OR SURGICAL:
MEDICAL (manual evacuation of the colon, laxatives, prokinetics, frequent walks, high fibre/low residue diet)
SURGERY (subtotal colectomy)

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Prognosis - megacolon

Good

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Post-op complications of megacolon- 5

Recurrent constipation
Increased defaecatory frequency
soft to watery faeces
tenesmus
rectal prolapse

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Describe possible colorectal neoplasias and their frequency

BENIGN (50%) - adenomatous polyps (up to 50% show malignant transformation), leiomyomas
MALIGNANT (50%) - adenocarcinoma (commonest), leiomyosarcoma, lymphoma, haemangiosarcoma, plasmacytoma

Which dog breeds are predisposed to adenocarcinomas? 4

GSD, Great Dane, Doberman, Boxer

Clinical signs - colorectal neoplasia - 6

tenesmus
haematochezia
increased defaecatory frequency
ribbon-like faeces (from being pushed past growth)
rectal prolapse 
weight loss

Diagnosis - colorectal neoplasia

RECTAL EXAM: 60-80% are in mid-caudal rectum. Check also for polypoid mass, irregular mucosal surface, annular stricture
RADIOGRAPHY - abdomen and thorax
ULTRASOUND - fine needle aspirate
COLONOSCOPY - grab biopsy

What catheter would you use to prevent a barium contrast coming back out of the anus?

Foley catheter (like a human urinary catheter)

Treatment - colorectal neoplasia - 2

Submucosal resection

- Wide surgical excision with intestinal resection and anastomosis

What causes anal relaxation that assists with submucosal resection?

An epidural (in addition to the GA)

Do you suture/staple when performing colorectal resection and anastomosis b/w pelvic bones

Stitches easier (space-wise) in this region

What do you do if you need to do a full thickness biopsy from the last part of the rectum?

Cut the rectum at the level of the anocutaneous junction and then pull rectum out

Prognosis - adenomatous polyps

Surgical resection --> can result in a cure. 17% recurr at 9-12mo, 25% malignant transformation at 9-17mo, median survival >2years (v good)

Prognosis - adenocarcinomas

Cure is possible with complete surgical excision due to low rate of distant metastases but complete excision often difficult due to tumour location. Medial survival 22 months

Prognosis if you use conservative management with faecal softeners

Median survival time 15 months

Prognosis - submucosal resection alone

A more benign surgery (complications resolve in 1 week), long term follow up - mean disease free interval = 37 months

3 causes of rectal prolapse

GIT parasites, rectal neoplasia, perineal hernia

Treatment - rectal prolapse - 4

Anthelmintics, faecal softeners, low residue diet, sedatives

Structure - anal sacs

Skin invaginations at 4 and 8 o'clock position within rectum

Clinical signs - anal sac impaction/inflammation/infection

HISTORY - perineal irritation (scooting, licking, biting, discomfort on defaecation) PE - enlarged non-painful/painful anal sac, secretions (normal - liquid brown, abnormal - thick white/yellow/green). Reddened inflamed skin or draining tract overlying region of anal sac suggestive of infection or ruptured abscess.

Treatment - anal sac impaction

Manual expression

Treatment - anal sacculitis/abscess

Sedation/anaestheisa, catheterise duct opening - lacrimal cannulae, collect sample (culute and cytology), lavage anal sac (0.9% saline), instill dexamethasone and ABs, systemic AB (if evidence of abscess or systemic disease), topical treatment (if yeast overgrowth is indicated on cytology)

Indication for anal sacculectomy types (2)

Repeat problems with anal glands. Can be an open or closed type.

Complication risk - anal sacculectomy

UNCOMMON - faecal incontinence - persistent infection with draining tracts

DDx for anal sac apocrine gland adenocarcinoma - 2

- PERIANAL ADENOMA - PERIANAL ADENOCARCINOMA - PARANEOPLASTIC SYNDROME (--> hypercalcaemia -> PU/PD)

Diagnosis and tumour staging - anal sac apocrine gland adenocarcinoma - 4

- PE (esp. sublumbar LNs) - Haematology, biochemistry, urinalaysis - Fine needle aspirate (usually sufficient for Dx)/incisional biopsy - radiography/ultrasound (thorax/abdomen)

Treatment - anal sac apocrine gland adenocarcinoma - 3

Combination (because hard to get a good margin around tumour) - surgery, radiation therapy, chemotherapy

Prognosis - anal sac apocrine gland adenocarcinoma

treatment with surgery - 548 d | all 3 - 956 days

How may anal furunculosis present?

May be just bleeding (GSDs prone especially)

Treatment - anal furunculosis

1. ) AB 2. ) immuno-modulatory therapy (cyclosporine = number 1 choice but very expensive) Alternative = ketoconazole (lowers dose of cyclosporine needed but has side effects so avoid)

Diagnosis - anal furunculosis

- Anaesthetise - Check anal sacs are intact (if not -remove) - Biopsy (-->culture, histopathology and determine if there is a significant bacterial component)

What is tacrolimus? Use?

Another immuno-modulatory drug that can be used for anal furunculosis but it is a cream therefore can't be used as a first line treatment but can keep lesions at bay long-term