A myriad of gastrointestinal (GI) diseases affect dogs and cats, with the most common being obstructive and nonobstructive foreign bodies, infectious, inflammatory, and neoplastic conditions. GI disease disrupts normal physiologic mechanisms and can lead to significant debilitation in dogs and cats, including hypovolemia, hypoproteinemia, electrolyte and acid–base imbalance, inflammation, perforation, and sepsis.^1-6 In the case of obstructive GI disease, acute vomiting can result in fluid and electrolyte losses, but the relative significance to overall fluid and electrolyte balance may be minimal with lower intestinal obstruction.^7,8 Clinically, however, hypochloremia, metabolic alkalosis, hypokalemia, and hyponatremia appear to be common in both upper and lower GI obstruction.⁴ Vomiting is a common sequela to GI obstruction that puts the patient at risk for aspiration pneumonia and further debilitation.⁸ Obstructed bowel becomes distended, hypersecretory, malabsorptive, hyper- or hypomotile, and ischemic, which can lead to microbial translocation and eventual perforation.^1,2,9-11 Intraluminal fluid accumulation appears to be significant in the upper GI tract in contrast to the lower intestinal tract, where minimal to no fluid accumulation occurs after acute obstruction for up to 72 hours.² Acute small intestinal obstruction also affects electromotor activity of the bowel.¹⁰ A pattern of orad hypermotility results initially, which progresses in an orad direction to the level of the proximal duodenum. Simultaneously, aborad to the obstruction, hypomotility results, which progresses aborad to the level of the terminal ileum.⁹ As chronicity develops, eventual diffuse intestinal ileus ensues.¹⁰ A significant and immediate reduction of intestinal blood flow occurs with intestinal obstruction at intraluminal pressures of 30 mm Hg. As intraluminal pressure increases beyond 30 mm Hg, a corresponding worsening of intestinal blood flow results until a residual 20% to 35% of original flow remains.¹¹ Oxygen extraction by the small intestine also declines as intraluminal pressure increases.¹¹

Nonobstructive or partially obstructive GI disease in dogs and cats may be associated with a more chronic and subtle onset of signs, including intermittent vomiting, gradual weight loss, mild hypoproteinemia, and hypokalemia.¹² Appropriate recognition and resuscitation of compromised patients before anesthesia and surgery is important regardless of whether or not laparoscopy is to be performed. A laparoscopic approach to GI surgery, when performed safely, should not present any significant additional risks versus a traditional laparotomy. Accordingly, the surgeon and ­support staff must be trained, experienced, and ready to convert to exploratory laparotomy in both elective and emergent situations if indicated.^13-15 GI laparoscopy is beneficial in staging and determining operability in certain cancers¹⁶ and is associated with minimal morbidity and improved patient recovery compared with more invasive methods in humans.¹⁷ Similar benefits likely exist with veterinary patients, but comparative studies have not been performed.

The GI tract in dogs and cats occupies most of the peritoneal cavity and extends from the esophageal hiatus of the diaphragm to the rectum in the pelvic canal. Therefore, complete gastroenteric exploration requires abundant working space and visibility within the majority of the peritoneal cavity. The stomach is divided into four major anatomic regions: the cardia, fundus, body, and pylorus. It is supported in position by surrounding soft tissues, including the esophagus and diaphragm; hepatogastric, hepatoduodenal, and gastrosplenic ligaments; and the liver and mesentery. In diagnostic GI laparoscopy, the ventral parietal gastric surface is readily visible, which facilitates evaluation. In contrast, the dorsal visceral surface is obscured by gravity and the surrounding adjoining soft tissues and thus requires alteration of patient position or gastric manipulation for evaluation in most cases. The pylorus is continuous with the descending duodenum at the cranial duodenal flexure, which is anchored in place by the hepatoduodenal ligament and the mesoduodenum. The descending duodenum originates in the right hypochondriac region and is anchored at the caudal duodenal flexure to the mesocolon.¹⁸ Consequently, laparoscopic evaluation of the stomach and descending duodenum is performed intracorporeally in most cases. The ascending duodenum continues craniosinistrally from the caudal duodenal flexure, where it dives dorsally to the mesentery of the remaining small intestine and transitions into the jejunum. The ascending duodenum and jejunum are only loosely tethered dorsally by a relatively long mesenteric root, which facilitates extracorporeal laparoscopic-assisted evaluation. At the ileocecocolic junction (ICJ), the mesenteric attachments become shorter and therefore anchor the ICJ and colon more dorsally and caudally in the abdominal cavity. As a consequence, exteriorization and extracorporeal evaluation is more difficult but accomplishable in most cases with a laparoscopic-assisted approach.

The preoperative diagnostic workup is typical of dogs and cats presenting with clinical signs of GI disease and is not usually different compared with patients undergoing laparotomy. In general, patients with GI disease should undergo preoperative complete blood count, serum biochemistry, urinalysis, coagulation testing, and appropriate diagnostic imaging. Dogs with GI hemorrhage may have a chronic nonregenerative anemia and associated azotemia. An inflammatory leukogram is common with many GI diseases. A degenerative, left-shifted leukogram with evidence of sepsis (e.g., hypoglycemia, hyperbilirubinemia) should raise the suspicion of septic peritonitis, currently a contraindication to laparoscopic-assisted GI exploration. Serum biochemistry and urinalysis allow for assessment of hepatic and renal function and fluid and electrolyte status and are helpful in targeted therapy and resuscitation. Although uncommon in an experienced minimally invasive surgeon’s hands, intraoperative hemorrhage was responsible for 85% of emergent diagnostic laparoscopic conversions in one study.¹³ Preoperative coagulation testing should therefore be considered in patients undergoing laparoscopic GI exploratory surgery, especially if biopsy of a vascular organ or mass is anticipated.

Selection criteria for diagnostic laparoscopic GI exploration have not been determined for dogs and cats. However, a recent study looking at conversion rates from diagnostic laparoscopy to laparotomy found that a low preoperative total solids, presence of a solitary liver tumor, and diagnosis of neoplasia were associated with an increased risk of conversion to laparotomy.¹³ In the same study, a total conversion rate of 21% was determined. There are currently only two clinical reports describing the use of diagnostic and therapeutic GI laparoscopy in dogs and cats.^14,15 Both of these studies used a laparoscopic-assisted technique to explore the GI tract and reported excellent outcomes with few complications. However, conversions were reported in both case series, and a number of limitations and potential contraindications were suggested. For example, lesion diameter appears to be important, and the author of this chapter considers an intestinal lesion diameter of approximately 5 cm to be a reasonable upper limit when considering a laparoscopic-assisted approach in most dogs and cats.¹⁵ Similar lesion sizes have been proposed in human laparoscopic-assisted GI surgery,¹⁷ but there are conflicting recommendations.^26,27 Large-diameter lesions require significant enlargement of the port incision and may obviate some of the benefits of a minimal approach. Because the bowel is tubular, the length of the lesion is not as important in regard to exclusion as long as the affected bowel can be exteriorized safely. GI lesion lengths of up to 9 cm have been reported to be amenable to a laparoscopic-assisted exploratory approach.¹⁴ The specific region of the affected bowel also appears to be important when considering patients as candidates for laparoscopic-assisted GI exploration. Dogs and cats with GI lesions affecting the stomach, orad duodenum, or bowel aborad to the ICJ may not be ideal candidates for a laparoscopic-assisted approach if significant exteriorization is required for complete evaluation and treatment.^14,15 Adhesions of the GI tract appear to be a contraindication to laparoscopic-assisted GI exploration in dogs and cats as well. Adhesions tether bowel to the mesentery and to other bowel segments, which results in the inability to safely exteriorize bowel from the peritoneal cavity without significant lengthening of port incisions.¹⁵ Dense GI adhesions are associated with an increased risk of conversion from laparoscopic-assisted to traditional GI surgery in humans for management of small bowel obstruction,²⁸ and caution should be exercised when considering a laparoscopic approach in veterinary patients with known adhesions.^14,15