A five-month-old female pomeranian dog (weighing 0.95 kg) with a history of cyanosis, exercise intolerance, and delayed growth presented to Veterinary Teaching Hospital, Gyeongsang National University. Findings on diagnostic imaging studies showed a dextropositioned and over-riding aorta, pulmonic stenosis, ventricular septal defect, right ventricular hypertrophy, and atrial septal defect. Based on the diagnostic findings, the dog was diagnosed as a case of tetralogy of Fallot with atrial septal defect (pentalogy of Fallot).