重度の貧血と止血不良を主徴とし，血液中の間接型ビリルビン濃度の増加と有棘赤血球の出現ならびに重度のヘモグロビン尿の排泄がみられた12歳，雄の雑種犬の1例について原因を検索した．血小板数の減少，出血時間・プロトロンビン時間および活性化部分トロンボプラスチン時間の延長，血漿フィブリノゲン濃度の低下，血液凝固第II，V，VII，VIII，IX，X，XIおよびXII因子の活性の低下を認め，可溶性フィブリンモノマー複合体とフィブリン分解産物が検出された．死後の病理検査では肝臓および脾臓に血管肉腫を認め，消化管粘膜の静脈内と腎糸球体にフィブリン血栓を確認した．本症例は犬の血管肉腫に合併した細小血管障害性溶血性貧血を伴う播種性血管内凝固症候群であった．
―キーワード：播種性血管内凝固症候群，犬，血管肉腫．

　Examination of a male, mixed-breed dog (12 years old) with severe anemia, bleeding tendency, increased serum indirect bilirubin concentration, acanthocytosis of the peripheral blood, and severe hemoglobinuria revealed thrombocytopenia, prolonged bleeding time, prothrombin time, and activated partial thromboplastin time, decreased plasma fibrinogen concentration, and activities of blood-coagulation factors II, V, VII, VIII, IX, X, XI, and XII. In addition, soluble fibrin monomer complex and serum fibrin/fibrinogen degradation products were detected. Postmortem histopathologic examination revealed hemangiosarcoma of the liver and spleen and fibrin thrombi in the veins of gastrointestinal mucosa and the glomeruli of the kidney. On the basis of these findings, the case was diagnosed as disseminated intravascular coagulation with microangiopathic hemolytic anemia complicated by hemangiosarcoma.
―Key words : disseminated intravascular coagulation, dog, hemangiosarcoma.