Primary omental abscessation or omental infarction in four dogs.

Primary omental abscessation was diagnosed in three dogs after laparotomy. Laparotomy was performed to explore an abdominal mass of unknown origin and chronic fat necrosis diagnosed in one dog as an incidental finding during ovariohysterectomy. Primarily hypoechoic masses not connected to any abdominal structures were visualized with abdominal ultrasound in three dogs. Suppurative inflammation was diagnosed from fine-needle aspirate evaluation in two dogs. Bacteria were cultured from two abscesses despite the absence of organisms on Gram stain, cytology, and histopathology. Foreign material was found in one abscess. All four dogs experienced weight loss and/or an episode of gastrointestinal signs. Primary omental abscessation may be preceded by omental vascular compromise and/or interaction of the omentum with foreign material.