hemodynamic disturbance-oedema in animals

1. Haemodynamic disorders
Dr. Jeny K John
Assistant Professor, Clinical Pathology
Department of Veterinary Clinical Pathology
COVAS, SVPUAT, Meerut

2. Hemodynamic disorders
 Hyperaemia and congestion
 Haemorrhage
 Oedema
 Thrombosis
 Embolism
 Infarction
 Shock

3. Oedema
 Condition characterized by an excessive accumulation of fluid in the
interstitial tissue spaces or body cavities
 Cellular oedema/ cellular swelling: abnormal fluid accumulation inside
cell
 Oedema can be generalized/ localized
 Anasarca: Generalized swelling of subcutaneous tissues occurs when
oedema is severe
 Hydroperitoneum/ Ascitis: Collection of oedema fluid in the peritoneal
cavity
 Hydrothorax: Fluid in pleural cavity
 Hydropericardium: Fluid in the pericardial sac
 Hydrocephalus: Fluid accumulation in ventricles of brain
 Hydrocele: Local accumulation of fluid in the tunica vaginalis of the
testicles

4. S.
No.
Characters Transudate Exudate
1 Colour Clear, water like pale yellow Cloudy, white, yellow-red
2 Consistency Thin, watery no tissue fragments Thick, creamy, contains tissue
fragments
3 Odour None Have odour
4 Ph Alkaline Acidic
5 Specific gravity 1.015 or less 1.018 or higher
6 Protein Low, < 3% High > 4%
7 Cell count Low High, RBCs, WBCs
8 Enzyme count Low High
9 Bacteria None Present
10 Inflammation None Present

5. Pathogenesis
 Oedema is the result of an increase in the forces that tend to remove fluids
from the intravascular compartments into the interstitial tissue spaces
 Exchange between intravascular and interstitial compartment is governed by
Starling’s forces
 According to Starlings hypothesis, the normal fluid balance is maintained by
two opposing sets of forces namely vascular hydrostatic pressure and plasma
osmotic pressure
 Fluid move from the intravascular to the interstitial compartment at the
arteriolar end of the microcirculation under the influence of hydrostatic
pressure
 It returns to intravascular compartment at the venular end mainly because of
the osmotic pressure
 2 forces balances so that only a small excess of fluid in the interstitial tissue
spaces- normally drained off through lymphatics …….No odema

6. Relationship of hydrostatic pressure and osmotic pressure in the
exchange of fluids through vessel walls in a normal resting leg
 Hydrostatic pressure at the arterial end of the capillary = 45 mm Hg
 Osmotic pressure at the arterial end of the capillary = 30 mm Hg
15mm rate of fluid into the tissues
 Osmotic pressure at the venular end of the capillary = 30 mm Hg
 Hydrostatic pressure at the venular end of the capillary = 15 mm
Hg
15mm rate of fluid into the veins

7. Oedema will occur when there is
1. Increase in intravascular hydrostatic pressure
2. A fall in colloid osmotic pressure in the plasma
3. Lymphatic obstruction
4. Sodium and water retention

8. 1. Increased hydrostatic pressure
 Results from impaired venous return
 Animals- less important and mild
 Occur in general and local passive hyperemia and is due to increased venous
hydrostatic pressure caused by a central obstruction in the heart or lungs or local
obstruction in a vein
 Hydrostatic pressure at the arterial end of the capillary = 45 mm Hg
 Osmotic pressure at the arterial end of the capillary = 30 mm Hg
15mm rate of fluid into the tissues
 Osmotic pressure at the venular end of the capillary = 30 mm Hg
 Hydrostatic pressure at the venular end of the capillary = 20 mm Hg
10 mm rate of fluid into the veins
Net result: 15mm Hg – 10mm Hg = 5 mm Hg
At the rate of 5 mm Hg fluid accumulates in the tissues
Usual cause of venous stasis is impaired cardiac function: Cardiac oedema

9. 2. Reduced plasma osmotic pressure
 Results from excessive loss or reduced synthesis of serum albumin
 Most common cause of oedema in animals
 Hypoproteinemia : Cattle and sheep occurs as a result of heavy infestation with
stomach worms and other intestinal parasites- loss of blood-Parasitic oedema
 Slowly bleeding gastric ulcers in dogs and pigs-Loss of blood-Hypoproteinemia
 Renal amyloidosis, glomerular nephritis – loss of blood protein- Renal oedema
 Less common in animals
 Advanced liver diseases such as cirrhosis leads to decreased synthesis of plasma
protein- Hypoproteinemia
 In starvation/malnutrition: reduced synthesis of protein by liver- Nutritional
oedema or cachectic oedema

10.  Hydrostatic pressure at the arterial end of the capillary = 45 mm Hg
 Osmotic pressure at the arterial end of the capillary = 20 mm Hg
25mm rate of fluid into the tissues
 Osmotic pressure at the venular end of the capillary = 20 mm Hg
 Hydrostatic pressure at the venular end of the capillary = 15 mm Hg
5 mm rate of fluid into the veins
Net result: 25mm Hg – 5 mm Hg = 20 mm Hg
At the rate of 20 mm Hg fluid accumulates in the tissues
This type of oedema is severe

11. 3. Lymphatic obstruction
Occurs from inflammatory (farcy; ulcerative lymphangitis) or neoplastic obstruction- tumors, cysts,
abscesses, bandages, rubber bands or harnesses press on lymph vessels
Also seen when tumors or thrombi are found in lymphatics or lymph nodes
Parasites (filariasis or Demodex canis mites)
Leads to local oedema
In lymphatic obstruction, fluid and protein in intercellular space will not be drained leading to oedema
(LYMPHOEDEMA)
 Hydrostatic pressure at the arterial end of the capillary = 45 mm Hg
 Osmotic pressure at the arterial end of the capillary = 25 mm Hg
20 mm Hg rate of fluid into the tissues
 Osmotic pressure at the venular end of the capillary = 25 mm Hg
 Hydrostatic pressure at the venular end of the capillary = 15 mm Hg
10 mm Hg rate of fluid into the veins
Net result: 20mm Hg – 10 mm Hg = 10 mm Hg
At the rate of 10 mm Hg fluid accumulates in the tissues

12. 4. Sodium and water retention
 Due to failure of excretion sodium in urine, water will be
retained leading to generalized oedema
 Sodium retention
Causes
 Congestive heart failure
 Nephrosis/Nephritis
 Acute renal failure

13. Macroscopical appearance
 Swollen, increase in weight
 Cold due to decrease blood flow and increase heat dissipation
 Less color
 No pain
 Incision results in flow of fluid from cut surface
 Pits on pressure
 Fibrosis
Microscopical appearance
 Space between adjacent cells widened
 During life space filled with fluid
 H&E stain - fine granular material - stains faintly pink - ↑ pink if ↑ protein
 Atrophy of parenchymatous cells
 Fibrosis - chronic cases

14. Significance and result
 Disappears if cause is removed
 Oedema in lung & brain are fatal
 Subcutaneous oedema impairs wound healing