The spleen is a relatively large organ in dogs and is located on the left side of the abdomen. The dorsal extremity, or head of the spleen, rests between the fundus of the stomach and the cranial portion of the left kidney; this is the least freely moveable portion of the spleen. It is suspended by part of the greater omentum, arising from the left crus of the diaphragm, which forms the phrenicosplenic ligament. This omental tissue also forms a wide gastrosplenic ligament, which attaches the hilus of the spleen to the greater curvature of the stomach. The ventral extremity of the spleen, or tail, has less restrictive omental attachments and is variable in position. Blood supply is from the splenic artery, which in most dogs originates from the celiac artery (but in a small number of dogs, the splenic artery can originate from the cranial mesenteric artery.²⁴ This blood supply branches into approximately 25 branches that fan out at the splenic hilum. Venous drainage from the spleen is through the splenic vein, which drains into the gastrosplenic vein. Care needs to be taken especially in cats to avoid iatrogenic damage to the pancreas which runs in close proximity to the splenic hilus within the mesentery. In dogs, the organs are more distant, but in both species, blood supply to the left limb of the pancreas, which emanates from branches of the splenic artery and veins, needs to be protected to avoid vascular insult to that area of pancreas.

Total splenectomy in canine patients is often performed through a standard ventral midline laparotomy with ligation of vessels along the splenic hilus; alternatively, ligation of the left gastroepiploic artery, short gastric arteries, and splenic artery and vein distal to the pancreatic blood supply may also be performed. Descriptions of LS have been specific to the former surgical technique (hilar splenectomy) because the hilar vessels are readily identifiable from a laparoscopic approach.

Identification of a splenic mass or lesion should prompt thorough evaluation of systemic health, including complete blood count, serum biochemistry profile, and urinalysis. Particular attention to red blood cell parameters and platelet counts is useful to determine ongoing or recent hemorrhage, as well as evaluation of immune-mediated or hemophagocytic disorders. When concern exists regarding coagulation ability, diagnostics to evaluate coagulation or platelet function should be evaluated preoperatively.

Thoracic radiographs are a necessary component of a comprehensive workup to evaluate for the presence of pulmonary metastatic disease. Echocardiography may be considered to look for a mass associated with the right atrium or atrial appendage, particularly when splenic hemangiosarcoma is thought to be a likely differential because concurrent cardiac involvement is known to occur in a significant number of cases.^25,26 Computed tomography (CT) of the thorax is another diagnostic imaging modality that has higher sensitivity for detection of pulmonary metastatic disease²⁷ and may allow identification of some larger cardiac tumors.

Abdominal ultrasonography is considered essential before LS for appropriate patient selection and surgical planning. Documentation of splenic size and presence of masses, concurrent hemoperitoneum or other abdominal effusion, and presence of concurrent intraabdominal disease is critical for determining the appropriateness of LS, as well as overall patient prognosis and outcome. Abdominal CT is recommended over ultrasonography in human medicine.⁹ CT may give a better sense of splenic size and shape; however, the degree of variability in splenic vasculature and ligamentous attachments seen in humans may make this information more essential in human medicine than in veterinary patients. Contrast-enhanced CT has been evaluated as a modality for differentiating splenic masses in dogs, and certain features, such as attenuation characteristics, were found to be helpful in differentiating benign from malignant lesions.²⁸ Magnetic resonance imaging has also been used for evaluation of splenic masses in dogs and was found to have very high sensitivity and specificity for differentiation of benign from malignant disease.²⁹

Fine-needle aspirates (FNA) of the spleen, liver, lymph nodes, or other intraabdominal abnormalities may be of utility in determining the etiology of disease before surgical intervention. Although FNA is a relatively safe and well-tolerated procedure that may shed light on the underlying disease process, splenic cytology alone has a reported accuracy rate of only 61.3% in one study,³⁰ and in another, complete agreement between cytologic and histologic diagnoses was only found in 51.4% of cases.³¹ Nonetheless, because of a positive predictive value of 86.7% for neoplastic disease, these findings may still be of use in guiding treatment decisions.

In human medicine, some authors suggest that LS should be used in all elective splenectomy cases unless portal hypertension, ascites, or traumatic splenic injury is present.⁹ Relative contraindications are controversial and include obesity and massive splenomegaly (>25 cm longitudinal length). Hand-assisted LS has been suggested as an alternative approach in cases of massive splenomegaly.¹²

At this time, recommendations for appropriate patient selection in veterinary medicine are empirical but include the absence of hemoperitoneum, the absence of massive splenomegaly, and splenic masses smaller than 6 cm in diameter. A case report describes the successful excision of a 3-cm splenic hemangiosarcoma in a canine patient via LS,²¹ and a case series of dogs that underwent LS for splenic masses up to 6 cm in size has been published.²³ Very large splenic masses are likely to hinder both visualization and the ability to manipulate the spleen with a laparoscopic approach. Large lesions may also be more friable and may rupture more easily during manipulation, although these are unconfirmed hypotheses at this time. Dogs with concurrent hemoperitoneum are currently not considered appropriate candidates for LS because of impaired visualization in the presence of free abdominal fluid and the need to obtain rapid hemostasis. Despite LS having been described for traumatic splenic rupture in humans,⁶ including a description of a technique for rapid control of the splenic hilum, no reports exist of acute hemorrhage control in LS in small animal patients. Dogs with large splenic masses are also prone to formation of extensive omental adhesions, which increases the difficulty of laparoscopic dissection. Because techniques for LS will progress in veterinary medicine, these concerns may be mitigated through improved instrumentation and surgeon proficiency with LS in the future.

Currently, no studies are available in the veterinary literature that have evaluated risk factors for conversion or complications in companion animal species. In humans, increasing body mass index, the presence of hematologic malignancy, and increasing splenic longitudinal diameter were all risk factors for complications in LS, and the first of these two factors were independent risk factors for conversion in one large multicenter study.⁸ Larger studies are necessary to evaluate these prognostic factors in small animal LS.

Preoperative preparation for LS is routine with recommended fasting overnight to avoid gastric distension at surgery. The patient’s bladder should ideally be expressed immediately before entering the operating room to ensure maximal working space within the peritoneal cavity. Perioperative antibiotics are administered intravenously during surgery (cefazolin 22 mg/kg every 90–120 ­minutes). The abdomen should be clipped for standard exploratory laparotomy from 3 to 5 cm cranial to the xiphoid process as far caudally as the pubis and laterally to the proximal third of the body wall on both sides. The possibility of conversion to an open approach should always be considered.