Difference between revisions of "Haemorrhage"

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<br>
 
==Introduction==
 
==Introduction==
 +
 
* Haemorrhage is the escape of blood from within the cardiovascular system.
 
* Haemorrhage is the escape of blood from within the cardiovascular system.
 
* Can be distinguished microscopically from congestion.
 
* Can be distinguished microscopically from congestion.
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** Neoplastic disease.
 
** Neoplastic disease.
 
* "Haemorrhagic diathesis" describes a predisposition to bleeding, either spontaneous or associated with trifling mechanical damage.   
 
* "Haemorrhagic diathesis" describes a predisposition to bleeding, either spontaneous or associated with trifling mechanical damage.   
** Often manifests as [[Haemorrhage#Purpura|purpuric disease]].  
+
** Often manifests as [[Haemorrhage - Pathology#Purpura|purpuric disease]].  
** Haemorrhagic diatheses and [[Haemorrhage#Purpura|purpura]] may be a feature of a number of diseases of different aetiology (poisoning, septicaemia or neoplastic disease).
+
** Haemorrhagic diatheses and [[Haemorrhage - Pathology#Purpura|purpura]] may be a feature of a number of diseases of different aetiology (poisoning, septicaemia or neoplastic disease).
  
 
==Types of Haemorrhage==
 
==Types of Haemorrhage==
 +
 
* Two main types of haemorrhage are recognised and are considered in more detail below:
 
* Two main types of haemorrhage are recognised and are considered in more detail below:
** '''[[Haemorrhage#Haemorrhage by Rhexis|Rhexis]]'''
+
** '''[[Haemorrhage - Pathology#Haemorrhage by Rhexis|Rhexis]]'''
 
*** Actual physical rupture of a vessel wall
 
*** Actual physical rupture of a vessel wall
** '''[[Haemorrhage#Haemorrhage by Diapedesis|Diapedesis]]'''  
+
** '''[[Haemorrhage - Pathology#Haemorrhage by Diapedesis|Diapedesis]]'''  
 
*** The escape of blood from vessels.
 
*** The escape of blood from vessels.
 
*** It may be difficult to detect a disruption to the vessel wall.
 
*** It may be difficult to detect a disruption to the vessel wall.
  
 
===Haematoma===
 
===Haematoma===
 +
 
* A large blood clot within the tissues.
 
* A large blood clot within the tissues.
 
** A localised collection of blood confined by surrounding tissues resulting in a modular formation.  
 
** A localised collection of blood confined by surrounding tissues resulting in a modular formation.  
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===In Body Cavities===
 
===In Body Cavities===
 +
 
* Haemothorax, Haemopericardium and Haemoperitoneum.
 
* Haemothorax, Haemopericardium and Haemoperitoneum.
 
** Blood escapes into the respective body cavities.
 
** Blood escapes into the respective body cavities.
  
 
===Petechiae===
 
===Petechiae===
 +
 
* These are minute - foci are 1-2mm in diameter.
 
* These are minute - foci are 1-2mm in diameter.
 
* Of capillary origin.
 
* Of capillary origin.
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===Ecchymoses===
 
===Ecchymoses===
 +
 
* Of capillary origin. .
 
* Of capillary origin. .
 
* Foci are 3-23mm in diameter.
 
* Foci are 3-23mm in diameter.
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===Purpura===
 
===Purpura===
* [[Purpura haemorrhagica|Purpura]] is a clinical syndrome.  
+
 
 +
* Purpura is a clinical syndrome.  
 
* Multiple small spontaneous haemorrhages develop in tissues (e.g. skin, mucosae, serosal surfaces and joints).
 
* Multiple small spontaneous haemorrhages develop in tissues (e.g. skin, mucosae, serosal surfaces and joints).
 
* A mixture of petechiae and ecchymoses.
 
* A mixture of petechiae and ecchymoses.
  
 
==Haemorrhage by Rhexis==
 
==Haemorrhage by Rhexis==
 +
 
* This is of venular or arteriolar (or larger vessel) origin.
 
* This is of venular or arteriolar (or larger vessel) origin.
 
** Results in major bleeding.
 
** Results in major bleeding.
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==Haemorrhage by Diapedesis==
 
==Haemorrhage by Diapedesis==
 +
 
===Septicaemia===
 
===Septicaemia===
 +
 
* Causes large numbers of petechiae and ecchymoses.
 
* Causes large numbers of petechiae and ecchymoses.
  
 
===Toxaemia and Poisoning===
 
===Toxaemia and Poisoning===
 +
 
* Causes petechiae and ecchymoses.
 
* Causes petechiae and ecchymoses.
 
** These haemorrhages are probably due to direct damage to the vessel walls.
 
** These haemorrhages are probably due to direct damage to the vessel walls.
  
 
===Purpura haemorrhagica===
 
===Purpura haemorrhagica===
 +
 
* Pupura haemorrhagica is a condition that occurs in horses after an infection.
 
* Pupura haemorrhagica is a condition that occurs in horses after an infection.
 
** Particularly following [[Respiratory Bacterial Infections - Pathology#Strangles|Strangles]].  
 
** Particularly following [[Respiratory Bacterial Infections - Pathology#Strangles|Strangles]].  
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===Haemophilia===
 
===Haemophilia===
 +
 
* Failure of the normal clotting of the blood.
 
* Failure of the normal clotting of the blood.
 
** Due to absence of one of the clotting factors.
 
** Due to absence of one of the clotting factors.
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===Dicoumeral poisoning===
 
===Dicoumeral poisoning===
 +
 
* Dicoumeral is an antagonist to Vitamin K.
 
* Dicoumeral is an antagonist to Vitamin K.
 
** Vitamin K is needed by the liver to synthesise prothrombin and various clotting factors.
 
** Vitamin K is needed by the liver to synthesise prothrombin and various clotting factors.
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==Gross Appearance of Haemorrhage==
 
==Gross Appearance of Haemorrhage==
 +
 
* The gross appearance of haemorrhage can vary depending on the tissue in which it occurs.
 
* The gross appearance of haemorrhage can vary depending on the tissue in which it occurs.
  
 
===Epistaxis===
 
===Epistaxis===
 +
 
* Epistaxis is a nose bleed.
 
* Epistaxis is a nose bleed.
 
* The haemorrhage may originate anywhere in the respiratory system.  
 
* The haemorrhage may originate anywhere in the respiratory system.  
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===Gastric Haemorrhage===
 
===Gastric Haemorrhage===
 +
 
* Gastric secretion soon turns the blood a dark brown.
 
* Gastric secretion soon turns the blood a dark brown.
 
* When vomited up it is called Haematomesis.
 
* When vomited up it is called Haematomesis.
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===Dysentery===
 
===Dysentery===
 +
 
* Occurs when the bleeding is low down the [[Alimentary System Overview - Anatomy & Physiology|alimentary tract]].
 
* Occurs when the bleeding is low down the [[Alimentary System Overview - Anatomy & Physiology|alimentary tract]].
 
* The blood is passed in the faeces relatively unchanged.
 
* The blood is passed in the faeces relatively unchanged.
  
 
===Haematuria===
 
===Haematuria===
 +
 
* Blood is present in the urine.
 
* Blood is present in the urine.
 
** Imparts a red colour to it.  
 
** Imparts a red colour to it.  
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===Bruising===
 
===Bruising===
 +
 
* Brusing is the result of haemorrhage.
 
* Brusing is the result of haemorrhage.
 
* Appears red for 48 hours and then begins to turn yellow.
 
* Appears red for 48 hours and then begins to turn yellow.
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==Effects of Haemorrhage==  
 
==Effects of Haemorrhage==  
 +
 
===Local===
 
===Local===
 +
 
* Haemorrhage may result in a diffuse mass of red blood cells and fibrin in loose connective tissues and in organs.
 
* Haemorrhage may result in a diffuse mass of red blood cells and fibrin in loose connective tissues and in organs.
 
** E.g. in the cutaneous connective tissues, the [[Spleen - Anatomy & Physiology|spleen]] and the gut wall.
 
** E.g. in the cutaneous connective tissues, the [[Spleen - Anatomy & Physiology|spleen]] and the gut wall.
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===Systematic===
 
===Systematic===
 +
 
* The systematic effects of haemorrhage are usually associated with uncontrolled blood loss.
 
* The systematic effects of haemorrhage are usually associated with uncontrolled blood loss.
 
** I.e. from a major artery associated with trauma.  
 
** I.e. from a major artery associated with trauma.  
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** Loss of 30-40 per cent in a few minutes is often fatal.
 
** Loss of 30-40 per cent in a few minutes is often fatal.
 
** Loss of over 50% over a 24 period may be tolerated in the dog.
 
** Loss of over 50% over a 24 period may be tolerated in the dog.
 
 
[[Category:Circulatory Disorders - Pathology]]
 
[[Category:Cardiology Section]]
 

Revision as of 15:28, 31 August 2010


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CIRCULATORY DISORDERS



Introduction

  • Haemorrhage is the escape of blood from within the cardiovascular system.
  • Can be distinguished microscopically from congestion.
    • Congestion - the blood remains within the vessels.
    • Haemorrhage - blood is seen outside the vessels.
  • Haemorrhage may be of capillary, venous, arterial and rarely cardiac origin.
  • May be external or internal (within body cavities).
  • Associated with:
    • Wounds or trauma.
    • Inflammation, where toxins are involved.
    • Neoplastic disease.
  • "Haemorrhagic diathesis" describes a predisposition to bleeding, either spontaneous or associated with trifling mechanical damage.
    • Often manifests as purpuric disease.
    • Haemorrhagic diatheses and purpura may be a feature of a number of diseases of different aetiology (poisoning, septicaemia or neoplastic disease).

Types of Haemorrhage

  • Two main types of haemorrhage are recognised and are considered in more detail below:
    • Rhexis
      • Actual physical rupture of a vessel wall
    • Diapedesis
      • The escape of blood from vessels.
      • It may be difficult to detect a disruption to the vessel wall.

Haematoma

  • A large blood clot within the tissues.
    • A localised collection of blood confined by surrounding tissues resulting in a modular formation.
  • Often sub-cutaneous.
  • May form space-occupying lesions.
    • E.g. in brain.

In Body Cavities

  • Haemothorax, Haemopericardium and Haemoperitoneum.
    • Blood escapes into the respective body cavities.

Petechiae

  • These are minute - foci are 1-2mm in diameter.
  • Of capillary origin.
  • Usually seen on the skin, mucous membranes and serosal surfaces.

Ecchymoses

  • Of capillary origin. .
  • Foci are 3-23mm in diameter.
  • Are blotchy.
  • Often confluent.
  • Usually seen on the skin, mucous membranes and serosal surfaces.

Purpura

  • Purpura is a clinical syndrome.
  • Multiple small spontaneous haemorrhages develop in tissues (e.g. skin, mucosae, serosal surfaces and joints).
  • A mixture of petechiae and ecchymoses.

Haemorrhage by Rhexis

  • This is of venular or arteriolar (or larger vessel) origin.
    • Results in major bleeding.
  • There are several causes of haemorrhage by rhexis.
    • Trauma.
    • Haemorrhagic enteritis.
    • Erosion of blood vessels by tumours or abscesses.
    • Idiopathic rupture of arteries.
  • In the horse intrapericardial rupture of the aorta may occur, although this is uncommon.

Haemorrhage by Diapedesis

Septicaemia

  • Causes large numbers of petechiae and ecchymoses.

Toxaemia and Poisoning

  • Causes petechiae and ecchymoses.
    • These haemorrhages are probably due to direct damage to the vessel walls.

Purpura haemorrhagica

  • Pupura haemorrhagica is a condition that occurs in horses after an infection.
  • Endothelial damage is caused by accumulation of immune complexes.

Haemophilia

  • Failure of the normal clotting of the blood.
    • Due to absence of one of the clotting factors.
  • Rare.
  • Reported in dogs and pigs.

Dicoumeral poisoning

  • Dicoumeral is an antagonist to Vitamin K.
    • Vitamin K is needed by the liver to synthesise prothrombin and various clotting factors.
  • Occurs with:
    • Warfarin poisoning
      • Warfarin is a common rat poison)
    • Prolonged feeding of sweet clover.

Gross Appearance of Haemorrhage

  • The gross appearance of haemorrhage can vary depending on the tissue in which it occurs.

Epistaxis

  • Epistaxis is a nose bleed.
  • The haemorrhage may originate anywhere in the respiratory system.
  • Can occur in the lungs following heavy exercise in the horse.
    • Appears bright red and perhaps frothy.

Gastric Haemorrhage

  • Gastric secretion soon turns the blood a dark brown.
  • When vomited up it is called Haematomesis.
  • Blood originating in the stomach and upper small intestine that is passed through the anus and is called Melena.

Dysentery

  • Occurs when the bleeding is low down the alimentary tract.
  • The blood is passed in the faeces relatively unchanged.

Haematuria

  • Blood is present in the urine.
    • Imparts a red colour to it.
  • It is important to distinguish this from haemoglobinuria.
    • In haemoglobinuria, the breakdown products of red blood cells appear in the urine following intravascular haemolysis.
    • In haemorrhage, the red blood cells will separate out and sediment to the bottom of a test tube.

Bruising

  • Brusing is the result of haemorrhage.
  • Appears red for 48 hours and then begins to turn yellow.
    • Due to macrophages converting haemoglobin into haemosiderin.

Effects of Haemorrhage

Local

  • Haemorrhage may result in a diffuse mass of red blood cells and fibrin in loose connective tissues and in organs.
    • E.g. in the cutaneous connective tissues, the spleen and the gut wall.
  • Alternatively, a local accumulation may form a haematoma and become a space- occupying lesion.
    • This may interfere with organ function.
      • E.g in intracranial haemorrhage, haemopericardium, and pulmonary haemorrhage.

Systematic

  • The systematic effects of haemorrhage are usually associated with uncontrolled blood loss.
    • I.e. from a major artery associated with trauma.
  • Rate of loss is critical, e.g.
    • Loss of 30-40 per cent in a few minutes is often fatal.
    • Loss of over 50% over a 24 period may be tolerated in the dog.