VPP 211: General Veterinary Pathology (1+1)

HAEMORRHAGE

Definition

• It is the escape of blood from a vessel.

Two types

• Haemorrhage by rhexis : When there is rupture of a blood vessel
• Haemorrhage by diapedesis : When blood leaves through intact blood vessels

Site of haemorrhage

Epistaxis	Bleeding from nose
Haematemesis	Blood in vomit
Haemoptysis	Blood in sputum
Metrorrhagia	Bleeding from uterus
Enterrohagia	Bleeding from intestine
Melena	Blood in stools
Haematuria	Blood in urine
Haemothorax	Blood in thoracic cavity
Haematocoel	Bleeding into tunica vaginalis
Hemosalphinx	Bleeding in oviducts
Hematoma	Tumour-like accumulation of blood
Apoplexy	Haemorrhage into brain

Apoplexy

Size of haemorrhage

• Petechiae: minute; pinpoint
• Purpura: approximately 1cm in size
• Ecchymoses: 1 – 2 cm in size
• Extravasation: Larger area

Petechiae-Intestine	Purpura - Spleen	Ecchymoses - Spleen

 

Extravasation	Internal haemorrhages-Abdominal cavity

Source of haemorrhage

• Cardiac
• Arterial
• Venous
• Capillary

Causes

• Conditions affecting the blood vessels
• Conditions affecting the blood

Conditions affecting blood vessels

• Trauma: Lacerations, incisions, contusions
• Clumps of bacteria, swine erysipelas, anthrax, haemorrhagic septicaemia
• Necrosis of vessel wall
  • Ulcers in gastric mucosa
  • Neoplasms
• Diseass of vessel walls
  • Aneurysm - e.g. Strongylus vulgaris infection in horses
  • Atheroma
• Toxic injury to capillary endothelium
  • Bacterial : Anthrax, haemorrhagic septicaemia, black quarter
  • Viral : Hog cholera
  • Chemicals : Arsenic, phosphorus, chloroform, cyanide
  • Enterotoxins : Sheep & calves – Clostridium welchii - ASPHYXIA
• Increased blood pressure
  • Excessive exercise → increased blood pressure → Rupture of blood vessel - Seen in race horses
• Hypoxia and lack of nutrition
  • Passive venous congestion → damage to endothelium - Haemorrhage

Conditions affecting blood constituents

• Haemophillia: Hereditary sex linked disease; Delayed clotting
• Thrombocytopenic purpura: Decrease in platelets seen in toxaemias
• Nutition
  • Deficiency of vitamin K
    • Vitamin K which is required for prothrombin  formation and in its absence clotting will not take place.
    • Increased use of sulpha drugs may not permit intestinal microflara to synthesis vitamin K
  • Deficiency of vitamin C
    • Vitamin C  is required for formation of ground substance. Invitamin C defeciency capillary endothelium becomes more fragile leading to haemorrhage
• Heparinoid state
  • In anaphylactic shock and irradiation, excess of  heparin is found which impairs clotting.
• Plant toxins
  • Brakern fern and sweet clover poisoning prevent prothrombin formation

Microscopical appearance

• Presence of erythrocytes outside blood vessels
• Recent haemorrhage stains deeply

Haemorrhage disintegrates due to action of tissue enzymes

↓

Haemoglobin ® Haemosiderin (Iron) and hamatoidin (Non iron)

↓

Bilirubin

↓

Phagocytosed by macrophages

• Prussian blue reaction reaction to demonstrate iron

Significance and result

• Depends on volume, rate, site. Sudden loss of about 30% of blood volume  or slow losses of large volume of blood will have no clinical significance. e.g. Stomach worm infection
• Site of haemorrhage is very important. Small haemorrhage in brain is fatal whereas small haemorrhage in skeletal muscle or subcutaneous tissue is NOT FATAL. Haemorrhage in pericardial sac (CARDIAC TAMPONADE) is fatal.
• Iron deiciency anaemia is due to repeated and chronic loss of blood from external surface
• When erythrocytes are retained in body cavities, joints, tissues, iron is recaptured and haemoglobin is synthesized.

Fate of haemorrhage

• In small haemorrhage fluid portion is reabsorbed, WBCs move into blood vessels and RBCs are phagocytosed
• In larg haemorrhage, RBCs are haemolysed and haemoglobin is split into haeme (Haemosiderin which is iron containing portion of haeme and haematoidin is iron free portion) and globin. 

Arrest of haemorrhage

Vascular contraction	Small blood vessels
Platelet aggregation	White clot
Clot formation	Red clot → When blood flow is slow
Tissue pressure	Increased perivasular pressure in tissue Decreased intra vascular pressure
Decreased blood pressure	Large harmorrhage ↓ Decreased BP ↓ No bleeding