Spontaneous thrombotic occlusion of a patent ductus arteriosus in an adult dog.

A 7-year-old Pomeranian with a history of patent ductus arteriosus (PDA) was presented with acute hindlimb paralysis. Hindlimb aortic thrombosis (ATh) was suspected, and spontaneous PDA thrombus was incidentally identified on echocardiography and computed tomography (CT). Concurrent protein-losing nephropathy was identified as the underlying condition contributing to the hypercoagulable state. Low-dose antithrombotic therapy was initiated to minimize the risk of abrupt PDA recanalization, which could result in cardiovascular compromise. Despite treatment, distal ATh progressed, resulting in renal infarction, acute kidney injury, and death. This report describes a rare case of spontaneous PDA closure without surgical or interventional treatment. Thrombotic PDA occlusion should be considered in hypercoagulable dogs with a history of PDA and no audible murmurs. Echocardiography and arterial-phase CT can help in establishing a diagnosis. This case highlights the importance of close monitoring and individualized treatment in dogs with PDA and prothrombotic risk factors.