Pulmonary thromboembolism (PTE) is an infrequently diagnosed complication of many systemic diseases including heartworm disease, glomerulopathy leading to the nephrotic syndrome, immune‐mediated hemolytic anemia, hyperadrenocorticism, pancreatitis, neoplasia, and sepsis. Acute, unexplained dyspnea in a patient with minimal abnormalities on thoracic radiographs should prompt consideration of this diagnosis. Confirmation requires ventilation‐perfusion radionuclide scanning or selective pulmonary angiography. Treatment includes cage rest, anticoagulant therapy with heparin and warfarin, correction of the underlying disorder, and supportive care. Clinicians should be prepared to treat hemorrhage associated with anticoagulant therapy. Recombinant tissue plasminogen activator may prove useful as a thrombolytic in the treatment of animals suffering massive PTE, but is, at present, expens