AbstractObjectiveTo report the diagnosis and treatment of a companion dorper wether with patent ductus arteriosus (PDA).Study designCase report.AnimalAn 8‐month‐old dorper wether presented to its primary care veterinarian for a persistent cough and was referred for suspected heart failure on the basis of physical examination and thoracic radiography. A PDA was diagnosed on echocardiography.MethodsThe sheep underwent cardiac catheterization and angiogram to measure pulmonary arterial and right ventricular (RV) pressures, identify the morphology of the PDA, and determine whether an intravascular occlusion of the PDA was feasible. Pulmonary artery pressure was 84/53 mm Hg (mean = 66), and RV pressures were 79/5 mm Hg (mean = 45); these were consistent with pulmonary hypertension. The size and shape of the PDA precluded vascular occlusion. Instead, the PDA was ligate through a left fourth intercostal approach.ResultsThe sheep improved clinically after surgery. The PDA seemed closed on echocardiogram 3 days after surgery. Measurement of postoperative fractional shortening was consistent with decreased left ventricular systolic function that had resolved according to follow‐up echocardiography.ConclusionWe report the first known diagnostic evaluation and successful treatment of naturally occurring PDA in a companion sheep.Clinical significanceFor economically valuable small ruminants, radiographs, echocardiography and cardiac catheterization can be used to diagnose and plan surgical treatment of PDAs, with a potential for a good long‐term outcome.