An intact male, 3-year old, Sapsari, weighing 29 kg with a history of respiratory distress, anorexia, abdominal distension, and depression for 1 day was referred. Radiographic findings included a C-shaped soft tissue mass in the mid-abdominal cavity and loss of serosal detail. Ultrasonographs showed splenomegaly with hypoechoic coarse parenchyma, loss of venous flow in the dilated splenic veins, and thrombi. Based on image findings, acute isolated splenic torsion was diagnosed. Splenectomy and prophylactic gastropexy was performed. Another case was a spayed female, 8-year old, Shih-tzu, weighing 3.7 kg with a history of intermittent abdominal pain and a palpable abdominal mass for 1 year. Radiographic findings showed splenomegaly characterized by a soft tissue round mass. Ultrasonographs revealed displaced splenic hilum and absence of venous flow in the dilated splenic vein. Chronic isolated splenic torsion was diagnosed and also splenectomy and gastropexy was performed. Two dogs were recovered normally after surgery without any complications. Acute form of isolated splenic torsion showed acute systemic clinical signs, severe C-shaped splenomegaly on radiographs, and loss of all of splenic venous flow, perivenous hyperechoic triangle sign, and thrombi on ultrasonographs. Chronic form of isolated splenic torsion showed chronic obscure clinical signs, moderate splenomegaly on radiographs, and partial loss of splenic venous flow on ultrasonographs.