7 - Large Intestines Flashcards
What are 6 indications for surgery of the large intestines?
- Obstruction
- Perforation
- Torsion/entrapment
- Colonic inertia (megacolon)
- Chronic inflammation
- Rectal prolapse
What is NOT an indication for surgery of the large intestine?
routine biopsy
What is a colotomy?
Incision into the colonic lumen
What is a colectomy?
Partial or complete resection of the colon
What is a colopexy?
Surgical fixation of the colon
What is a colostomy?
Creation of an artificial opening into the colonic lumen
What is the most common reason for R&A of the colon?
tumor
What is megacolon?
Increased colon diameter and hypomitility associated with severe constipation
What species most commonly gets idiopathic megacolon?
cats
What are the 4 steps for medical treatment of megacolon?
- Evacuate colon
- Antibiotics
- Osmotic laxatives (lactulose)
- Prokinetic drugs (cisapride)
What is the approach to surgical treatment of megacolon?
- Removal of entire colon except a short segment needed to re-establish intestinal continuity
- Subtotal colectomy
- +/- address pelvic stenosis
What are 2 ways by which we can do a subtotal colectomy?
Ileocolic anastomosis or colocolic anastomosis
What is typhlectomy?
Removal of the cecum
What are 5 indications for a typhlectomy?
- Impaction
- Perforation
- Inversion
- Severe inflammation
- Neoplasia
What are 2 indications for a colopexy?
- Chronic rectal prolapse
- Recurrent perineal hernia
What side should a colopexy be done on?
left
Why is a colostomy rarely performed?
Animals don’t do well with it -
Fecal incontinence occurs and there are very high management requirements
What are the 2 main approaches to the rectum?
- Ventral midline celiotomy
- Caudal/transanal approach
What 2 procedures/techniques can be done at the rectum with a caudal/transanal approach?
- Mucosal eversion
- Rectal pull-through
What part of the GIT has the most bacteria?
GIT
T/F: Empty and cleanse after large intestine surgery is no longer recommended.
True
Why should perioperative antibiotics be given with large intestine surgery?
There is a high risk of infection with coliforms and anaerobes
What perioperative antibiotics should be given with large intestine surgery?
2nd or 3rd generation cephalosporins, cefazolin, metronidazole
Why does the large intestine take longer to heal?
Collagen lysis, poor collateral, # bacteria, pressure
What are medical treatments for rectal prolapse?
- Treat underlying disease
- Reduce (lavage and lube)
- Purse string around anus
What types of lesions would be considered for surgical treatment of a rectal prolapse?
Chronic, traumatized, non-reducible lesions
What is used as a guide in surgical treatment of rectal prolapse?
rectal probe
In surgical treatment of rectal prolapse, _____ should be placed cranial to the transection site.
stay sutures
Rectal prolapses should be transected in _____.
stages
What type of closure is used for a rectal prolapse transection and what are the margins?
Appositional closure, 2 mm from edge and 2 mm apart
What should be done after closing the transection of a rectal prolapse?
Reduce anastomosis into pelvic/anal canal
What muscles support the caudal rectum?
- Levator ani
- Coccygeus
- External anal sphincter m.
What is the role of the internal and external sphincter mm?
Control continence
What innervates the internal anus/perineum?
- Parasympathetic branch of pelvic n. (S1-3)
- Sympathetic motor from hypogastric n.
What innervates the external anus/perineum?
Caudal rectal branch of pudendal n.
The caudal rectal branch of the pudendal n. is _____ and responsible for _____.
voluntary, continence
What is the main vascular supply to the anus/perineum?
- Internal pudendal a.
- Caudal rectal a.
- Caudal mesenteric a.
- Cranial rectal a.
Where are the anal sacs located?
Between inner smooth and outer striated mm. (between internal and external sphincters)
The anal glands line the _____ and open into the _____.
wall, sac (intermediate zone)
What are the 2 most important diagnostic steps to make a working diagnosis regarding the anus/perineum?
- Visual inspection
- Palpation
What are 2 reasons not to do a rectal exam?
- No finger
- No anus
Fecal incontinence occurs if more than ___ cm or the final ___ cm of terminal rectum is resected.
4cm, 1.5cm
Fecal incontinence occurs if _____ or _____ nerves are damaged.
perineal, caudal rectal
Fecal incontinence occurs if more than half of the _____ is damaged.
external anal sphincter
What are the 2 most common anal sac diseases?
Infection or impaction
How should anal sacculitis be medically managed?
Expression, lavage, AB’s, dietary change, treat dermatoses
What should not be used in medical management of anal sacculitis?
chemical cauterization
When should anal sacculitis be surgically managed?
When there is an abscess or if it is chronic/recurrent
What are DDx for a perianal fistula?
- SCC
- Perianal tumors
- Anal sac fistula
- Pythiosis
- Tail fold pyoderma fistula
What is the more common treatment for a perianal fistula?
Medical - Clyclosporine
Which type of anal sacculectomy has less risk of contamination? Which should you never do when there is suspected neoplasia?
Closed, Open
What 5 diagnostics can help us determine if there is an anal neoplasia?
- Rectal palpation
- Imaging
- Cytology
- Labwork (look for hypercalcemia)
- Histopath
80% of anal neoplasias are _____.
perianal adenomas
What sex is more likely to develop a perianal adenoma?
intact male (12x)
Perianal adenomas are hormone _____.
dependent
What is treatment for perianal adenomas?
Castration +/- local excision
What types of carcinomas can occur as an anal neoplasia?
Perianal or apocrine
When are anal sac adenocarcinomas common? When are they rare?
Common in older dogs;
Rare in cats
Anal sac adenocarcinomas have a _____% metastatic rate to local LNs at time of Dx.
50-80%
What blood work level would be abnormal in an anal sac adenocarcinoma and what mediates this?
Hypercalcemia of malignancy;
Mediated by PTHrp
What are the treatments for anal sac adenocarcinomas?
- Primary tumor excision
- LN removal if enlarged
- Chemo +/- RT
What does atresia ani lead to?
Inability to defecate normally
What does a rectovaginal or rectourethral fistula lead to?
Abnormal communication and passage of feces
What is the medical treatment for fecal incontinence?
Treat causative disease, low residue diet, opioids, enemas, and rectal stimulation
