Hypothermia

Patients often become hypothermic during surgery, and core temperature should be monitored intraoperatively, especially in small animals, debilitated animals and during long procedures. Using warmed fluids for abdominal lavage is beneficial. Careful but aggressive warming in the postoperative period with use of water blankets, foil covers, Bair huggers etc., will ensure timely rewarming. Close monitoring to avoid overheating is also critical.

Pain

Adequate postoperative analgesia is critical for patients undergoing gastrointestinal surgery, especially in the first 12–24 hours. Options include epidurals or spinals (morphine), constant rate infusions (hydromorphone/lidocaine, fentanyl, ketamine/morphine/lidocaine), or repeat intravenous administration of opioid or other analgesics.

Gastro-Oesophageal Reflux and/or Vomiting

Reflux or vomiting is fairly often noted (and sometimes present but not noted!) during or following gastrointestinal procedures. Suctioning of the oesophagus (if animal is still under anaesthesia) and institution of an H2 blocker is recommended, along with nil per os (NPO) for 12 hours. Monitoring for aspiration pneumonia is also indicated in refluxing patients. Sucralfate is not indicated unless gastrointestinal ulceration is present.

Renal Shutdown

It is very common to give insufficient fluids during long or major abdominal procedures, and also fail to catch up in the postoperative period. In most cases, renal perfusion can be gauged by measuring urine production through a urethral catheter (> 2 ml/kg/hour). In more critical cases, a central line (and sometimes arterial line) should be placed and central venous pressure measurements will provide feedback on vascular volume. If a patient's urine production falls in the face of previously normal cardiac and renal evaluations, crystalloid fluids can be administered as a bolus, usually as 500 or 1000 ml. Colloids such as hetastarch will also pull volume into the vascular space. Persistent hypoperfusion may require furosemide, or a pressor agent (dobutamine, dopamine). These agents should only be used when adequate vascular volume is assured. If systemic blood pressure stays below a mean of 60 mmHg for more than 4–6 hours, permanent renal failure may ensue.

Pancreatitis

Surgical pancreatitis can occur from intraoperative retraction and handling of the pancreas (try to avoid this), especially following duodenal or hepatic surgery. Signs include cranial abdominal discomfort or pain, and vomiting, developing several days after surgery. Serum amylase and lipase may be elevated, and ultrasonography can also confirm. Traumatic pancreatitis is usually self-limiting and will resolve over several days on intravenous fluids and parenteral nutritional support. Occasionally, a fulminating necrotising pancreatitis will develop, with a poor prognosis.

Body Wall Dehiscence, Herniation or Evisceration

If the body wall has not been securely closed, or if the suture material was inadequate, breakdown of the linea suture line and herniation of omentum and sometimes intestines will occur. Evisceration of abdominal contents can follow, along with self-trauma and rapid clinical deterioration. Incisional herniation is usually diagnosed on clinical presentation of a soft fluctuant swelling (unless strangulation or incarceration have occurred), which is usually reducible. Evisceration is self-evident and is an emergency. Immediate reoperation and resection is indicated, as well as aggressive management for peritonitis.

Intestinal Suture Line Dehiscence and Peritonitis

One of the most critical of all complications is the breakdown of an intestinal suture line, leakage of contents into the peritoneal cavity and ensuing peritonitis. Gastric dehiscence is uncommon, due to the rich vascular supply and the usual two-layer closure. Most dehiscences will occur within 3–5 days of surgery. An initially improved postoperative patient will become lethargic and inappetent.

Heart rate and temperature may rise, and vomiting, abdominal pain and distension can (but will not always) develop. Haematology values tend to show an increase in the white blood cell count and percentage of bands, and decrease in platelets. Toxic changes will be seen associated with the left shift. With colonic dehiscence, marked deterioration will occur within hours. Diagnostics should include abdominal radiography, and abdominocentesis. Ultrasonography can be useful to determine presence of early abdominal effusion. If a tap is not diagnostic, diagnostic peritoneal lavage is indicated. Remember that air can be present in the abdominal cavity for up to a week following abdominal surgery, as well as mature neutrophils and a few bacteria (not intracellular).

Treatment is immediate reoperation, with supportive therapy, including fluids, antibiotics and any further drugs to maintain cardiovascular function. The original coeliotomy incision is reopened and retracted, and thorough inspection of all abdominal contents is warranted. Cases of intestinal dehiscence require resection and anastomosis. An omental wrap or serosal overlay is indicated. Copious lavage and suction, exit culture and placement of abdominal drains are performed. Intensive postoperative monitoring and support is instituted - cardiorespiratory support, vascular volume maintenance, maintenance of renal perfusion, appropriate antibiotics, abdominal drainage, nutritional support and gastric decompression.

Short Bowel Syndrome

Short bowel syndrome is seen with the removal of 75–80% of the small intestinal tract. Maldigestion (due to decreased digestive enzyme production from proximal resections), malabsorption (due to decreased mucosal area and rapid transit time), bacterial overgrowth, bile salt and fatty acid loss into lumen will result in a clinically intractable osmotic diarrhoea, steatorrhoea and weight loss. Gastric hypersecretion can result in marginal ulceration and exacerbate the diarrhoea.

The severity of the syndrome depends on the amount resected, location of the resection, concurrent disease, the condition of the remaining bowel, the amount of time allowed for adaptation, and preservation, or not, of the ileocolic valve. At least a month should be allowed for adaptation. During this time, hydration and electrolyte status should be monitored and intravenous fluids maintained as necessary. Parenteral nutrition may also be useful in the first week. Frequent, small offerings of a highly digestible diet with vitamin, mineral and enzyme supplements should be instituted. An elemental diet is preferred, with glutamine, if not already supplemented. If steatorrhoea is present, a low-fat diet can be given, but diets low in fat are not usually palatable and have a low energy density. Gastric hypersecretion can be somewhat reduced with H2 antagonists, and antidiarrhoeal agents such as loperamide may help control the diarrhoea. Bacterial overgrowth can be treated with antibiotics.

Inadvertent Abdominal Foreign Body

In human surgery, retained sponges or instruments are associated with a prolonged, difficult or haemorrhagic procedure, or when the surgeon is rushed. Although metal instruments may not cause any signs, adhesions can eventually develop, causing some poorly defined signs or intestinal obstruction. Needles sometimes cause a problem if migration and perforation of a hollow viscus occurs. By far the most common object to accidentally leave behind is a surgical sponge (gossypiboma) - so use only large laparotomy sponges in the abdomen! An intense granulomatous inflammatory reaction can occur as the body tries to wall off the sponge. This can involve the gastrointestinal tract, pancreas, ureters, kidneys and also cause a draining tract through the retroperitoneal space to the skin (often the flank area). Reoperation is indicated and removal of the offending object and the adhesions (often involving resections) are indicated. Allow for a long surgery.

Less Common Complications That We Have Encountered!

Other complications that we have been 'fortunate' enough to see in our institution include:

 Postoperative ileus is uncommon in small animals, and usually associated with marked hypovolaemia or developing peritonitis. Poor technique such as drying of the intestines and aggressive handling will also contribute to its occurrence. It is a good idea to feed patients the day following surgery, listen for borborygmi and keep hospitalised until they defecate.

 Portal vein thrombosis following surgery in hypercoagulable patients (e.g., Cushingoid). This is manifested as deterioration following thrombosis in the postoperative period, signs of portal hypertension (abdominal effusion, pain, haemorrhagic diarrhoea, cardiovascular collapse). Upon reoperation, marked bowel discoloration and distension may be evident, but not in all cases. Portal pressures should be taken, even if a thrombus cannot be palpated. Removal of part or all of the thrombus may be possible through a portal venotomy. Insertion of a portal vein catheter (via splenic or left gastric vein) to allow pulsing sprays of thrombolytic agents such as streptokinase may prove useful.

 Permanent adhesions following gastrointestinal surgery are quite uncommon in small animals, especially if the principles of good intestinal surgery are followed. There appears to be a small percentage of animals that develop sclerosing peritonitis, in which a fibrous dry sac encapsulates the viscera. This carries a poor prognosis.

 Strictures are not common with appositional suture patterns. Inverting suture patterns in small bowel can lead to stricture formation and signs of obstruction. This is corrected by reoperation, resection and anastomosis.

References

1.  Bonczynski JJ, Ludwig LL, et al. Comparison of peritoneal fluid and peripheral blood pH, bicarbonate, glucose, and lactate concentration as a diagnostic tool for septic peritonitis in dogs and cats. Veterinary Surgery 2003;32:161–166.

2.  Gorman SC, Freeman LM, et al. Extensive small bowel resection in dogs and cats: 20 cases (1998–2004). Journal of the American Veterinary Medical Association 2006;228:403–407.

3.  Hauptman JG, Walshaw R, et al. Evaluation of the sensitivity and specificity of diagnostic criteria for sepsis in dogs. Veterinary Surgery 1997;26:393–397.

4.  Mueller MG, Ludwig LL, et al. Use of closed-suction drains to treat generalized peritonitis in dogs and cats: 40 cases (1997–1999). Journal of the American Veterinary Medical Association 2001;219:789–794.

5.  Ralphs SC, Jessen CR, et al. Risk factors for leakage following intestinal anastomosis in dogs and cats: 115 cases (1991–2000). Journal of the American Veterinary Medical Association 2003;223:73–77.