ANSWERS

1. What is an isotonic solution?
   A solution which exerts an equal osmotic pressure to that of body fluid.
2. What is a hypotonic solution?
   A solution which exerts a lower osmotic pressure than that of body fluid.
3. What is a hypertonic solution?
   A solution which exerts a higher osmotic pressure than that of body fluid.
4. When a hypertonic solution is administered during fluid therapy, why should an isotonic solution also be given?
   When a hypertonic solution enters the extracellular fluid, water is drawn out of the cells into the extracellular fluid resulting in cellular dehydration.
5. Which pharmaceutical companies manufacture crystalloids licensed for veterinary use?
   • Aquapharm.
   • Vetivex.
6. What is a crystalloid solution?
   A sodium based electrolyte solution of a composition similar to that of plasma water. Crystalloids pass readily through cell membranes, which means that they do not remain in the ECF but equilibrate with the ICF.
7. List some crystalloid solutions.
   • Normal saline.
   • Hartmans (lactated Ringers).
   • Ringers.
   • Darrow's.
   • Sodium chloride 0.9% and glucose 5%.
   • Plasmalyte.
   • Glucose 5%.
   • Sodium chloride 0.18% and glucose 4%.
   • Potassium chloride.
   • Sodium bicarbonate 8.4%.
8. What is a colloidal solution?
   A solution containing large particles which do not easily leave the vascular space. These therefore expand the plasma volume, and are subsequently often known as "plasma expanders". The scientific definition of a colloid is: a chemical system composed of a continuous medium of small particles which do not settle under the influence of gravity, nor pass through a semi-permeable membrane.
9. List common colloidal solutions.
   • Dextran (Dextran 70).
   • Gelatine (Haemaccel and Gelofusin).
   • Hetastarch.
10. What problems are associated with the use of Dextrans?
    • Antigenic.
    • Interference of cross matching of blood (by coating the red blood cells).
    • Promotion of cell clumping.
    • Haemolysis.
    • Cellular dehydration (a crystalloid solution should also be administered to avoid this).
11. What is the fluid of choice for a bitch suffering from pyometra and why?
    Hartmans; due to considerable sodium and potassium losses in the uterine discharge.
12. What is the fluid of choice in cases of diarrhoea and why?
    Hartmans; this provides calcium and bicarbonate to compensate for alimentary losses, and combats the resultant metabolic acidosis.
13. What fluid would be most suitable for a dog with chronic heart failure and why?
    5% Glucose infusion; this does not contain sodium, which may cause a heart condition to deteriorate.
14. What is Mannitol and when would its use be indicated?
    A hypertonic solution used to promote osmotic diuresis in cases of poisoning, cerebral oedema and glaucoma.

A Key Notes table - Fluid Types And Their Uses - accompanies this module.