Thoracoscopy is a minimally invasive imaging method used in the imaging of the thoracic cavity. In comparison with thoracotomy, thoracoscopy provides better visualization of even the smallest lesions localized in the thoracic cavity. With the use of thoracoscopy, the operation stress in the patient and tissue trauma are reduced, and operating time is shortened. The aim of this study was to evaluate 20 dogs with severe pericardial effusion, which manifested as severe circulation disorder and respiratory distress. The patients determined with pericardial effusion as a result of radiographic and echocardiographic examinations were applied with partial pericardiectomy to achieve permanent health and it was decided to apply this with the minimally invasive thoracoscopic method. The paraxiphoid-transdiaphragmatic approach was applied to the first ten patients and the intercostal approach to the latter. Applicability of thoracoscopic partial pericardiectomy, advantages compared to open surgery, differences between two approach techniques, disadvantages, complications, and success rates were evaluated. It was concluded that this procedure was a successful procedure for dogs and the transdiaphragmatic approach was more useful. In conclusion, thoracoscopic partial pericardiectomy was determined to be easy to apply and more advantageous than open thoracotomy operations.