Surgical approach to the colon, rectum and anus in small animals Flashcards
colorectal surgery - surgical approaches
Ventral Midline Laparotomy
Dorsal Perineal Approach
pelvic split
transanal
colotomy
Full thickness biopsy of the colon
Same basic principles as enterotomy
risk of infection + wound breakdown
Large intestinal resection & anastomosis
Same basic principles as for small intestine, but must
respect delayed healing of large intestine
How much colon can you remove?
Removal of majority of colon - Loss of reservoir & absorptive capacities, ↑fecal frequency, watery faeces
Preservation of ileocaecolic junction - preserves ileal function, Prevents retrograde flow of colonic bacteria into SI -↓risk of bacterial overgrowth
how much rectum can be removed
Rectal resections of 6cm or more are consistently
associated with faecal incontinence
Large intestinal anastomosis - sutures - aims
Optimise wound healing
Faster gain in tensile strength
Minimise decrease in lumen diameter
Decreased incidence of complications
Large intestinal anastomosis - staples
Rapid and reliable
Inserted via an incision in the caecum or via the anus
inverted anastomosis
Post-op bleeding
Higher anastomotic bursting pressures on day 7 compared to sutured anastomoses
complications of colorectal
Dehiscence & septic peritonitis Wound infection Abscess Faecal incontinence Stricture & tenesmus Rectal prolapse haematochezia
megacolon - define
Flaccid enlargement of the colon, distension of the colon
with feces and loss of function of the colonic muscle
when would you find Primary/idiopathic megacolon
in cats
secondary megacolon - causes
pelvic fractures intrapelvic space-occupying lesions Colorectal neoplasia Colorectal abscess Perineal hernia Inappropriate diet
megacolon - clinical signs
Chronic constipation, tenesmus, vomiting, anorexia, weight loss
Large colon containing fecal material, dehydration, poor body condition
Rule out underlying cause for constipation
megacolon - treatment
Treat underlying disease
Medical - Manual evacuation of colon, Laxatives, Prokinetics, Frequent walks, High fibre, low residue diet
Surgery - subtotal colectomy
Post-op complications - Recurrent constipation, Increased defaecatory frequency, Soft to watery faeces, Tenesmus, Rectal prolapse
Prognosis - Good
colorectal neoplasia
50/50 benign vs malignant
benign - Adenomatous polyps, leiomyomas - can transform to be malignant
malignant - Adenocarcinoma, leiomyosarcoma, lymphoma,
haemangiosarcoma, plasmacytoma
Colorectal neoplasia - signalment
Older dogs: 6-9 yrs
Adenocarcinomas
Colorectal neoplasia - history
Tenesmus Haematochezia Increased defecatory frequency Ribbon-like faeces Rectal prolapse Weight loss
Colorectal neoplasia: diagnosis
Rectal exam - polypoid mass, irregular mucosal surface, annular stricture
Radiography: abdomen & thorax
Ultrasound, fine needle aspirates
Colonoscopy, grab biopsy
Colorectal neoplasia: treatment
Submucosal resection
Wide surgical excision with intestinal resection &
anastomosis
colorectal neoplasia - prognosis
Adenomatous polyps - Surgical resection can result in a cure, 17% dogs: recurrence at 9-12 months, 25% dogs: malignant transformation at 9-17 months, Median survival > 2 years
Adenocarcinomas - Cure is possible with complete surgical excision due to low
rate of distant metastasis, but complete excision o
ften difficult due to tumour location, Median survival: 22 months
Conservative management with fecal softeners - Mean survival time: 15 months
Rectal prolapse - causes
Gastrointestinal parasites
Rectal neoplasia
Perineal hernias
Rectal prolapse - treatment
Anthelmintics
Faecal softeners
Low residue diet
Sedatives
Anal sac impaction, inflammation & infection
History - Perineal irritation: scooting, licking or biting,
discomfort on defecation
Physical Exam - Enlarged non-painful/painful anal sac
Abnormal 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
Anal sac impaction, inflammation & infection - treatment - medical
Impaction - Manual expression
Anal sacculitis/abscess - Sedation or anaesthesia, Catheterise duct opening: lacrimal cannulae, sample for culture and cytology, Lavage anal sac with 0.9% saline, dexamethasone and antibiotics
Systemic antibiotics, if evidence of abscess or systemic disease
Topical treatment of yeast overgrowth if indicated on cytology
Anal sac impaction, inflammation & infection - treatment - surgical
anal sacculectomy
anal sacculectomy - Complications
uncommon
Fecal incontinence if dissection was traumatic or aggressive - usually temporary unless both caudal rectal nerves were cut
Persistent infection with draining tracts - fail to remove all anal sac tissue
Anal sac apocrine gland adenocarcinoma
Highly malignant: 50% metastases at diagnosis
Anal sac apocrine gland adenocarcinoma - Perianal adenoma
benign, Common, Intact male, spayed females, Castration plus surgery
Anal sac apocrine gland adenocarcinoma - Perianal adenocarcionma
Malignant, Rare, Treat as anal sac adenocarcinoma
Anal sac apocrine gland adenocarcinoma - Paraneoplastic syndrome
Hypercalcaemia
polyuria and polydipsia
Anal sac apocrine gland adenocarcinoma - diagnosis
Physical exam
Haematology, biochemistry, urinalysis
Fine needle aspirate/ incisional biopsy
Radiography /ultrasound of thorax and abdomen
Anal sac apocrine gland adenocarcinoma - treatment
Surgery
Radiation therapy
Chemotherapy - mitoxantrone
Anal sac apocrine gland adenocarcinoma - prognosis
Treatment incl. Surgery – 548 days
All 3 of the above – 956 days
