Equine GI Surgery 2 Flashcards
- Define a crisis.
- Usual causative GI lesions in an abdominal crisis.
- Life-threatening.
No response to medical treatment alone and so only options are surgical intervention or euthanasia. - Obstruction of SI e.g. ileal impaction.
Obstruction of blood supply to gut
e.g. strongylus vulgaris infarcts.
Or both e.g. strangulating lipoma.
Simple obstructions.
Lumen only obstructed:
- with food, possible ascarids, rarely FB, faecolith, or choleolith.
Vasculature intact so intestine minimally compromised.
Prognosis usually good - many won’t need surgery.
E.g. ileal / pelvic flexure impaction.
Functional obstruction.
Peristalsis fails to propel ingesta i.e. ileus, leading to distension.
Vasculature intact so intestine minimally compromised.
Prognosis depends on aetiology.
E.g. grass sickness, post-op ileus secondary to distension, infiltrative or inflammatory bowel diseases e.g. lymphoma and eosinophilic enteritis.
NB pressure necrosis may follow esp. with non-ingesta impaction a such as ascarids and faecoliths.
Strangulation.
Compromise to vasculature — intestinal ischaemia.
E.g. pedunculated lipoma, large colon volvulus.
Veins obstructed before arteries, causing oedematous thickening of gut wall.
Bacterial death by changes in environment as now anaerobic and acidic - release of LPS.
Mucosal damage so increased permeability to endotoxin which leaks into peritoneum.
Peritoneal LPS absorbed into systemic circulation.
Endotoxaemia causes systemic compromise or shock.
Px becomes poorer after 6-8hrs.
- further worsened by secondary problems e.g. bacteria translocate from lumen as barrier ineffective, setting up potential for peritonitis.
- endotoxaemia may lead to DIC or laminitis.
Abdominal surgery options.
Emergency colic surgery - ex lap.
Elective surgery - ex laparoscopy / laparotomy.
Focused elective surgery:
- nephrosplenic space obliteration for left dorsal displacement.
- biopsy collection in chronic weight loss case.
- hernia repair.
- non-GI — mass excision e.g. granulosa cell tumour / cryptorchid castrate.
Preparation of horse for surgery after induction.
Fine clip of abdomen for midline ventral incision.
Covers on distal limbs and tail.
Urinary catheter placed.
Suture prepuce closed in males.
Sterile prep of abdomen.
Drape.
Equine abdominal surgery approach.
Midline ventral incision.
Umbilicus towards caudal limit.
Approx. 30cm long in 450kg horse, extend as needed.
Through skin.
Through linea alba - start at umbilicus, incise cranially.
Through peritoneum.
In a healthy horse, what should be the first structure visible as you enter peritoneum?
Caecum - Apex points towards xyphoid process.
Principles of surgical treatment - abdominal exploration.
Logical sweep around abdomen to palpate anomalies.
Exteriorise caecum if in normal position.
SI - trace dorsal taenial band of caecum to ileum, then exteriorise this and continue orally until obstruction reached.
— obstruction may be exteriorisable or not. Correct it and continue until can palpate the duodenocolic ligament.
LI - identify pelvic flexure and exteriorise this. Extend it maximally from incision.
— may require deflation and/or correction to exteriorise.
Principles of surgical treatment
- correction of the lesion.
Identify lesion.
Correct displaced/entrapped intestine.
Decompress distended viscera.
- evacuate toxic contents of devitalised segment once exteriorised.
- oral SI contents “milked” into caecum +/- caecal dump after anastomosis performed.
- LI contents evacuated through enterotomy at pelvic flexure.
Resection of devitalised tissue and restoration of intestinal continuity (anastomosis).
All needs to be done quickly with minimal trauma, keeping exteriorised intestines moody at all times.
Principles of surgical treatment - abdominal closure.
Swab count.
Replace intestines in normal anatomical position.
- Logical sweep around abdomen.
Lavage with sterile saline.
Anti-adhesion treatments - carboxymethylcellulose,
Simple continuous absorbable linea alba.
SC continuous absorbable layer.
Skin sutures (absorbable, non-absorbable) or staples.
Stent sutured over wound.
What artery supplies the jejunal arteries?
What artery branches to form ileal artery?
Cranial mesenteric artery.
Caecocolic artery.
Purpose of surgery in cases of simple/functional obstructions.
Remove obstruction.
Decompress point of lesion and backlog.
Usually milk ileal impaction into caecum as cannot exteriorise.
Consequences of strangulating lesions.
4-5hrs - mucosal necrosis.
7+hrs - serosal necrosis.
Spontaneous rupture.
Severe endotoxaemia.
Resection of strangulating lesions.
Identify non-viable tissue.
Ligate vessels in mesentery supplying devitalised segment.
May “dump” contents once separated from mesentery.
Isolate with double bowel clamps and Penrose drains.
Cut with scalpel between clamps.
Resection of devitalised intestine.
What type of suture is used in an intestinal anastomosis?
Inverting.
Give example of inverting suture pattern.
Connell, Cushing’s, Lembert’s.
Anastomosis after resection of strangulating lesion from intestine.
Site close to agreement artery has a good blood supply.
Segments with similar diameter.
- possible to do a 50-60 degree angle from mesentery to widen opening without creating kink.
Sutures/staples:
- described as the 2 anatomical locations.
— e.g. jejuno-jejunal. Jejuno-ileal, jejunocaecal, ileo-caecal.
— prognosis poorer when caecum involved.
- can be end-to-end, side-to-side, end-to-side.
Check integrity (no leaks), no kinks/torsion, no luminal restriction.
Close the mesentery.
