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28 Cards in this Set
- Front
- Back
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What is meant by the terms haemorrhage?
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escape of blood from the cardiovascular system
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What is meant by the terms haemoptysis?
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coughing of blood
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What is meant by the terms haematemesis?
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vomiting of blood
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What is meant by the terms haematochezia?
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passege of fresh blood in faeces
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What is meant by the terms epistaxis?
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bleeding from the nose
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What is meant by the terms melaena?
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diffuse, dark red-black discolouration of faeces due to upper alimentary tract haemorrhage or swallowing of blood from the respiratory tract
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What is meant by the terms petechiae?
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tiny, pinpoint foci of haemorrhage, 1-2mm in diameter
typically found in skin and on mucosal memb and serosal surfaces |
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What is meant by the terms purpura?
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slightly larger haemorrhages than petechiae
>3mm in diameter |
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What is meant by the terms ecchymoses?
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larger foci of haemorrhage
2-3cm in diameter usually blotchy and of irregular shape |
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What is meant by the terms paintbrush?
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linear or streaky haemorrhages, especially over serosal or mucosal membranes
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What is meant by the term haematomas?
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a palpable, discrete, space-occupying mass of clotted blood within tissues
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What is the most common cause of haemorrhage?
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mechanical trauma to blood vessels
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What are other potential causes of haemorrhage?
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-inflammation, degeneration or necrosis of a vessel wall
-invasion of vessel by a neoplasm -rapture of capillaries due to ↑d plasma P(hydro) -neutritional disorder (eg. VitE↓ in pigs) -ionising radiation -bacterial, viral infection etc |
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What factors determine the significance of haemorrhage?
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location, rate, and volume of haemorrhage
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What are the significant differences in terms of prognosis between internal and external haemorrhage?
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Internal haemorrhage (=haemorrhage into tissues or body cavities)→ plasma proteins and iron can be reutilised and some extravasated RBCs may be resorbed into lymphatics and returned to the circulation
external haemorrhage → blood lost from the body, no resorbtion! if prolonged, it may lead to hypoproteinaemia, iron deficiency anaemia |
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How do bruises and haematomas resolve?
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extravasated RBCs are ultimately removed by lysis or phagocytosis
Bruises change colour as time passes: red-blue(poorly deoxygenated haemoglobin) → blue-green(biliverdin&bilirubin) → gold-brown (haemosiderin, haematoidin +/- ceroid-lipofuscin) haematomas become enveloped by granulation tissue and ultimately coverted to scar tissue |
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What is meant by the term haemorrhagic diatheses?
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clinical disorders of haemostasis characterised by a bleeding tendency, with either spontaneous haemorrhage or excessive bleeding in response to minor trauma
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List the four main mechanisms by which primary haemostatic bleeding disorders develop.
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1.Platelet deficiency (=thrombocytopenia)
2. platelet dysfunction (= thrombocytopath) 3. von Willebrand's disease 4. vessel wall defects |
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List the three main mechanisms by which secondary haemostatic bleeding disorders develop.
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1. hereditary coagulation factor deficiency
2.Vitamin K antagonism or deficiency 3. Hepatobiliary disease |
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What clinical features would help you distinguish between an animal with a primary haemostatic bleeding disorder and one with a secondary haemostatic disorder?
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●Primary
-perechia common -bleeding from mucosal memb -bleeding from multiple sites -bleeding immedieately a/f venipuncture ●Secondary -petechia rare -bleeding into musscles, joints. and/or body caavities, or may be localised -delayed bleeding a/f venipuncture |
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What is meant by the term disseminated intravascular coagulation (DIC)?
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a complex acquired disorder of haemostasis that commences with widespread activation of blood coagulation within the microcirculation and may progress to sustained fibrinolysis and paradoxical haemorrhage
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What are the major mechanisms by which DIC can be triggered? What are some disorders that commonly trigger DIC?
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1. release of tissue factor or tissue factor-like procoagulant factors into the circulation
2. widespread endothelial injury |
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What are the key events in DIC?
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●Release of tissue facor and coagulation due to sepsis, tissue destraction, endothelia injury etc. (↑thrombin generation & coagulation inhibitors )
●widespread thrombosis within the microcirculation ●consumption of clotting factors and platelets. Fibrinolysis due to activation of plasmin. Ischemic tissue damage due tu vascular occlusion ●Bleeding!!!Hypocoagulable!! |
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What is meant by the terms microangiopathic haemolytic anaemia (fragmentation anaemia)?
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anaemia due to fragmentation trauma to circulating erythrocytes because of formation of fibrin strands within the microcirculation
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What is meant by the terms schistocytes?
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erythrocytes damaged by shearing forces (←they are bizarre shape)
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If an animal is bleeding due to DIC, what are the characteristic features of the bleeding?
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-may be spontaneous or triggered by venipuncture
-mafinests as mucosal and/or cutaneous petechiae and ecchymoses, epistaxis, deep haematomas, bleeding into body cavities etc |
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What clinical signs might suggest that an animal has developed DIC?
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higly variable!!
if animals are in the decompensated phase of DIC, they may show signs of shock, organ failure, dyspnoea, cyanosis or extreme respiratory distress, oliguria(↓d urine formation), sezures, coma haemorrhage or haemolytic anaemia |
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If an animal has died in DIC, what possible lesions might you expect to find at necropsy?
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mucosal, serosal and cutaneous petechiae and ecchymoses, deep haemotomas and haemorrhage within body cavities
microscopically identifiable thrombi in tissues in association with oedema, congestion, haemorrhage and/ or ischaemic necrosis |
