A 3-year-old neutered male guinea pig (Cavia porcellus) presented with abnormal mentation, anorexia, and a reduced number of feces. On physical examination, a heart murmur was auscultated on the right side of the chest, and bloating was detected on abdominal palpation. Radiological imaging revealed an abnormal cardiac silhouette and gastric volvulus. Ultrasound examination showed reduced blood flow in the hepatic lobes and gallbladder enlargement. Bloodwork indicated elevated AST levels. Laparotomy was performed, revealing the omentum and spleen displaced over the stomach. The gallbladder was markedly enlarged, displaying multiple vessels on its wall and containing yellowish fluid. Fluid from the gallbladder was aspirated for culture and sensitivity testing. The gallbladder was excised and sent for histopathological analysis. The stomach was repositioned following gallbladder and partial liver excision, and the abdomen was closed. Bacterial culture results were negative. Histopathology revealed severe focal hepatic necrosis, papillary hyperplasia of the gallbladder mucosa, and focal cholecystitis. The patient recovered well post-surgery, with no complications observed following the gallbladder excision.