A 7 yr old German shorthaired pointer presented with progressive respiratory distress and lethargy. Two weeks prior to presentation, the dog had porcupine quills removed from the left forepaw, muzzle, and sternal area. At the time of presentation, the dog had bounding pulses and friction rubs in the right dorsal lung field. Harsh lung sounds and decreased lung sounds were ausculted in multiple lung fields. Radiographs revealed a pneumothorax and rounding of the cardiac silhouette suggestive of pericardial effusion. Computed tomographic imaging was performed and revealed multiple porcupine quills in the thoracic cavity. Surgery was performed and quills were found in multiple lung lobes and the heart. Following surgery the dog remained hypotensive. A post-operative echocardiogram revealed multiple curvilinear soft-tissue opacities in the heart. Given the grave prognosis the dog was subsequently euthanized and a postmortem examination was performed. A single porcupine quill was discovered in the left atrium above the mitral valve annulus. The quill extended across the aortic root, impinging on the coronary artery below the level of the aortic valve. To the authors' knowledge, this is the first known report of porcupine quill migration through the heart.