Surgical Significance of Middle Hepatic Vein Proximity to the Gallbladder Fossa During Canine Cholecystectomy in Two Dogs.

The middle hepatic vein (MHV) may lie in close proximity to the gallbladder fossa and represent a potential source of severe hemorrhage during cholecystectomy. While this anatomical relationship is well recognized in human surgery, the clinical relevance of MHV proximity during canine cholecystectomy has rarely been described. Two dogs underwent cholecystectomy for gallbladder disease. In Case 1, an 8-year-old Pomeranian with gallbladder mucocele and necrotizing cholecystitis developed sudden massive hemorrhage during dissection of the gallbladder from the hepatic fossa between the quadrate and right medial liver lobes, when a branch of the middle hepatic vein (MHV) adherent to the gallbladder wall ruptured, causing rapid hypotension (mean arterial pressure 10-20 mmHg). Hemostasis was achieved using hemoclips, and the dog recovered following transfusion. In Case 2, an 11-year-old Spitz with a gallbladder mass underwent cholecystectomy and liver biopsy. Preoperative computed tomography demonstrated MHV branches coursing within <1 mm of the gallbladder wall. Careful dissection preserved the venous structures, and surgery was completed without significant hemorrhage. MHV branches may occur immediately adjacent to the gallbladder fossa in dogs and may represent an underrecognized source of hemorrhage during cholecystectomy. Awareness of this relationship and preoperative vascular evaluation in selected cases may improve surgical safety.