Axillary artery tumor embolism secondary to mitral valve myxosarcoma in a dog

To describe the clinical presentation, treatment, and outcome of a dog with an arterial tumor embolism.

An 11-year-old, neutered male Irish Setter presented with acute right forelimb lameness. The dog was unable to bear weight on the right forelimb, which was cool to the touch with no palpable pulses. Diagnosis of thromboembolism was confirmed using angiography, revealing a lack of blood flow to the right axillary artery. Balloon angioplasty, thrombosuction, and infusion of the thromboembolism with tissue plasminogen activator were used to achieve increased, but not complete, blood flow through the vasculature. Echocardiogram revealed vegetative mitral valve lesions consistent with endocarditis, thrombus, neoplasia, or a combination thereof. At the time of discharge, there was improvement in the temperature and motor function of the proximal limb but no conscious proprioception or deep pain sensation in the distal limb. Histopathologic analysis of the sample retrieved with thrombosuction was consistent with a diagnosis of myxosarcoma. A series of 3 rechecks showed continued improvement in neuromuscular function. Treatment for suspected mitral valve myxosarcoma was declined. The patient was lost to follow up until being presented for necropsy 16 months later. Necropsy confirmed myxosarcoma of the mitral valve with tumor emboli to the coronary arteries, lungs, and the right axillary artery.

To the authors' knowledge, there is no report of myxosarcoma originating on the mitral valve in dogs, although it has been reported in the human literature. To the authors' knowledge, there are also no reports of tumor embolism of the axillary artery in a dog. This case demonstrates a unique presentation of a dog that had a myxosarcoma tumor embolism. It also describes the use of angiography for diagnosis and localization of the vascular obstruction and a variety of interventional techniques for the treatment of thromboembolism.