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28 Cards in this Set

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What is meant by the terms haemorrhage?
escape of blood from the cardiovascular system
What is meant by the terms haemoptysis?
coughing of blood
What is meant by the terms haematemesis?
vomiting of blood
What is meant by the terms haematochezia?
passege of fresh blood in faeces
What is meant by the terms epistaxis?
bleeding from the nose
What is meant by the terms melaena?
diffuse, dark red-black discolouration of faeces due to upper alimentary tract haemorrhage or swallowing of blood from the respiratory tract
What is meant by the terms petechiae?
tiny, pinpoint foci of haemorrhage, 1-2mm in diameter

typically found in skin and on mucosal memb and serosal surfaces
What is meant by the terms purpura?
slightly larger haemorrhages than petechiae
>3mm in diameter
What is meant by the terms ecchymoses?
larger foci of haemorrhage
2-3cm in diameter

usually blotchy and of irregular shape
What is meant by the terms paintbrush?
linear or streaky haemorrhages, especially over serosal or mucosal membranes
What is meant by the term haematomas?
a palpable, discrete, space-occupying mass of clotted blood within tissues
What is the most common cause of haemorrhage?
mechanical trauma to blood vessels
What are other potential causes of haemorrhage?
-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
What factors determine the significance of haemorrhage?
location, rate, and volume of haemorrhage
What are the significant differences in terms of prognosis between internal and external haemorrhage?
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
How do bruises and haematomas resolve?
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
What is meant by the term haemorrhagic diatheses?
clinical disorders of haemostasis characterised by a bleeding tendency, with either spontaneous haemorrhage or excessive bleeding in response to minor trauma
List the four main mechanisms by which primary haemostatic bleeding disorders develop.
1.Platelet deficiency (=thrombocytopenia)

2. platelet dysfunction (= thrombocytopath)

3. von Willebrand's disease

4. vessel wall defects
List the three main mechanisms by which secondary haemostatic bleeding disorders develop.
1. hereditary coagulation factor deficiency

2.Vitamin K antagonism or deficiency

3. Hepatobiliary disease
What clinical features would help you distinguish between an animal with a primary haemostatic bleeding disorder and one with a secondary haemostatic disorder?
●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
What is meant by the term disseminated intravascular coagulation (DIC)?
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
What are the major mechanisms by which DIC can be triggered? What are some disorders that commonly trigger DIC?
1. release of tissue factor or tissue factor-like procoagulant factors into the circulation

2. widespread endothelial injury
What are the key events in DIC?
●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!!
What is meant by the terms microangiopathic haemolytic anaemia (fragmentation anaemia)?
anaemia due to fragmentation trauma to circulating erythrocytes because of formation of fibrin strands within the microcirculation
What is meant by the terms schistocytes?
erythrocytes damaged by shearing forces (←they are bizarre shape)
If an animal is bleeding due to DIC, what are the characteristic features of the bleeding?
-may be spontaneous or triggered by venipuncture
-mafinests as mucosal and/or cutaneous petechiae and ecchymoses, epistaxis, deep haematomas, bleeding into body cavities etc
What clinical signs might suggest that an animal has developed DIC?
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
If an animal has died in DIC, what possible lesions might you expect to find at necropsy?
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