Patent ductus arteriosus (PDA) is the most common congenital heart disease in dogs, and many pedigree dogs are susceptible. The diagnosis of PDA depends on complete cardiovascular examinations including auscultation and radiographic and echocardiographic examination. The treatment of left-to-right PDA with surgical ligation is excellent. However, the prognosis is guarded if right-to-left PDA existed. We published two female Maltese puppies with definite diagnosis as PDA and successful surgical correction.