An 8-year old intact female dog was presented with a sudden onset of unilateral hindlimb paralysis of 3 days duration. Based on the history and results of physical, neurological, histopathological examination, and blood work, an arterial thrombosis was suspected as a complication of the hypercoagulability from malignant mammary gland tumor. The thermography provided the evidence of the unilateral femoral thrombus. Initially, thrombolysis with streptokinase administered by intravenous infusion was ineffective. Thereafter, the direct delivery of streptokinase to the site of thrombus was attempted and it was curative. These results suggest that the thermography could describe the site of the arterial thrombus, and local intra-arterial administration of streptokinase may be an effective therapy for the canine arterial thrombosis complicated by malignant mammary gland tumor.