ABSTRACT. A 14-year-old spayed female cat weighing 2.3 kg developed tension pneumoperitoneum that progressed for 6 hr. Abdominocentesis was performed and 1.3 L of gas was aspirated after which the cat's respiratory condition improved. The next day, the cat's abdomen redistended, and laparotomy was performed. A gastric perforation was noted and sutured after the margin was resection. The cat showed a good physical condition without any gastrointestinal signs at 6 months after surgery. KEY WORDS: feline, gastric perforation, tension pneumoperitoneum.J. Vet. Med. Sci. 67(6): 617-619, 2005 Pneumoperitoneum refers to the presence of gas within the peritoneal cavity resulting from a ruptured hollow viscus, penetrating abdominal wounds or bacterial peritonitis [1]. Life-threatening, massive pneumoperitoneum necessitating immediate needle decompression to improve cardior e s p i r a t o r y e m b a r r a s s m e n t , k n o w n a s t e n s i o n pneumoperitoneum, has been reported in humans [2,4,11,13]. However, few reports have documented similar cases in veterinary fields. This study reports the case of a cat that developed tension pneumoperitoneum secondary to gastric perforation and was treated with abdominocentesis followed by laparotomy.A 14-year-old spayed female, domestic shorthair cat weighing 2.3 kg presented with marked abdominal distension that had been progressing for 6 hr. For 1 week prior to admission, the cat had been anorexic after a transient episode of vomiting. The owner described 6 episodes of vomiting during a 4-month prior to admission, which had always been resolved with symptomatic therapy for gastritis. The cat had also been affected with chronic rhinitis for several years.At the time of admission, the cat was collapsed in a recumbent position and was tachypneic with ballooned, tympanic abdominal distension. Heart rate was 180 beats per minute, and rectal temperature was 34.2°C. The mucus membrane was pale and purulent nasal discharge was noticed. Abdominal radiography revealed massive pneumoperitoneum with cranial displacement of the diaphragm, centralization of the abdominal organs, and a small amount of air within the contracted stomach (Fig. 1). Initial hematological abnormalities included a mildly low packed cell volume (32%), severe neutrophilia (42,240 cells/µL), and mild lymphopenia (880 cells/µL). Plasma biochemical analysis revealed high protein (9.6 g/dl), urea nitrogen (72 mg/dl), sodium (158 mEq/L) and chloride concentrations (121 mEq/L), and a low glucose concentration (63 mg/dl). The cat was seropositive for feline immunodeficiency virus antibody.Since abdominal radiographs suggested high intraabdominal pressure reducing diaphragmatic compliance, abdominocentesis was performed and 1.3 L of air was aspirated. The cat's respiratory condition returned to almost normal. After administration of 5% glucose (20 ml, IV), cefazolin sodium (20 mg/kg, SC), and enrofloxacin (5 mg/ kg, IM), the cat returned to the owner's care at home because it was late at night. The next morning, the cat...