Computed Tomography for Diagnosing Chylothorax Associated with Cranial Vena Cava Thrombosis in a Dog

A 13-year-old male neutered Miniature Pinscher presented with coughing and dyspnea.The dog had been coughing for the past 4 weeks.The patient had mild dehydration on physical examination, and muffled heart sounds were detected.Thoracic radiographs revealed pleural effusion, which was consistent with chylous effusion based on cytological and biochemical evaluations.Computed tomography (CT) lymphangiography, which was performed via intrametatarsal pad injection, revealed no evidence of thoracic duct rupture or obvious leakage.On CT angiography (CTA), an intraluminal filling defect was identified in the cranial vena cava (CrVC).CrVC thrombosis with secondary chylothorax was diagnosed based on CT lymphangiography and CTA.Clopidogrel, rivaroxaban, and recombinant tissue-plasminogen activator were prescribed.The follow-up CTA, 4 months after diagnosis, revealed a decrease in the thrombus, and no pleural effusion was identified.Although CrVC thrombosis is an uncommon presentation in veterinary patients, thrombus in the CrVC should be considered as a differential diagnosis of chylothorax in dogs.CT lymphangiography and CTA could be helpful in identifying and differentiating the underlying etiologies of chylothorax.