ANSWERS

1. What is meant by venipuncture?
   The collection of blood from a vein using a needle and syringe.
2. What veins are most commonly used for venipuncture in cats and dogs?
   • Cephalic
   • Jugular
3. What is a Vacutainer?
   A vacuum tube incorporating a double-ended needle screwed into a holder used for the collection of blood.
4. What are the main advantages of vacutainers?
   • Good sterility.
   • Less fiddly than a needle and syringe, and therefore quicker - meaning that there is less time for the blood to clot during collection.
   • Less chance of damaging the blood cells since they do not need to be transferred from syringe to specimen tube.
5. What are anticoagulants?
   Chemicals added to blood collection tubes to prevent the samples from clotting. Different types are necessary for different tests.
6. What is haemolysis?
   The disintegration of red blood cells as a result of trauma, contact with certain chemicals or osmotic changes.
7. List possible causes of haemolysis.
   • Putting blood through a narrow gauge needle.
   • Shaking the sample.
   • Pulling back hard on the syringe plunger.
   • Blood coming into contact with acid, alkali or alcohol.
   • Water on the blood collection tube, syringe or site of venipuncture.
8. Describe the effects of haemolysis on a blood sample.
   • Abnormally low RBC count and PCV due to the destruction of RBCs.
   • Interference with photometry due to the strong red colour of the plasma.
   • Abnormally high total protein level (if measurements taken using a refractometer).
9. What is lipaemia?
   The presence of lipids in the blood. This may be as a result of a metabolic condition, but is more likely to have arisen from a feed taken prior to blood collection. Fasting is therefore advisable.
10. What effects might lipaemia have upon a blood sample?
    • Falsely elevated biochemistry values, because of the effect of the resultant turbidity of the sample on light transmission in photometric measurements.
    • Increase in the likelihood of haemolysis during sample collection.
11. What is the difference between plasma and serum?
    • Plasma = the fluid portion of the blood in which the corpuscles are suspended.
    • Serum = the clear, fluid residue of blood, from which the corpuscles and fibrin have been removed. Therefore plasma is distinguished from serum in that serum is plasma from which the fibrinogen has been separated in the process of clotting.
12. What is meant by PCV?
    Packed cell volume. This is a percentage reading of the red cells present in a blood sample. It is a useful measurement for the assessment of anaemia (decreased reading) and dehydration (increased reading). PCV is also referred to as a haematocrit measurement.
13. State the normal range of PCV levels in dogs and cats.
    Dogs = 37-55% Cats = 30-45%
14. Why is EDTA the anticoagulant of choice for a blood sample from which a PCV measurement is to be taken?
    EDTA removes the calcium necessary for coagulation, whilst heparin interferes with the formation and activation of thrombin and only delays clotting.
15. In the assessment of dehydration, why is it sensible to use total plasma protein measurements in addition to PCV readings?
    Generally, each 1% increase in PCV above normal indicates a fluid loss of approximately 10mls/kg. Therefore, only an estimation of the percentage of dehydration may be performed unless the actual normal PCV is known (which it generally isn't).
16. What measurements may be taken from a quantitative buffy coat (QBC) analysis?
    • PCV.
    • Total white cell count.
    • Platelet coat.
    • Limited leukocyte differential.
    • Detection of microfilaria (blood parasites).
17. Give 3 examples of Romanowsky stains.
    • Diff-quik.
    • Giemsa.
    • Leishman's.
18. Describe the principle of the Romanowsky stains.
    2 Dyes are used: one of which stains basic tissue blue (haematoxylin), and the other which stains acidic tissue red (eosin). These stains are used for the examination of blood smears. They are ideal for differential cell counts and the staining of haemoparasites.
19. What is the difference between polychromasia and hypochromasia?
    Polychromasia is a differing intensity of staining of the red blood cells, whilst hypochromasia is simply understaining.
20. Why are the white cells found at the tail end of blood smears?
    They are heavier and are therefore swept to the end of the smear when it is prepared.
21. For what test would you use an Improved Neubauer Haemocytometer?
    A total white blood cell count.
22. State the 2 methods used for haemoglobin estimation.
    • Cyanmethaemoglobin Method.
    • Sahli method (rarely used).
23. What anticoagulant is used for the preservation of blood samples for biochemical tests?
    Heparin.
24. List conditions which may contribute to raised protein levels.
    • Dehydration.
    • Lactation.
    • Infection.
    • Neoplasia.
25. List conditions which may contribute to lowered protein levels.
    • Hepatic dysfunction.
    • Renal dysfunction.
    • Malabsorption.
    • Immunodeficiency.
26. List conditions which may contribute to raised cholesterol levels.
    • Hypothyroidism.
    • Cushings disease.
    • Post prandial (after feeding).
    • Diabetes mellitus.
27. List conditions which may contribute to lowered cholesterol levels.
    • Hepatic dysfunction.
    • Lipoprotein deficiency.
28. A lowered bilirubin level has no diagnostic significance, but what conditions may contribute to a raised measurement?
    • Hepatic dysfunction.
    • Haemolysis.
29. What blood parameter may be increased if an animal suffers one or more of the following conditions: hepatic anoxia, hepatoxins, hepatitis and metabolic disorders.
    ALT.
30. What is a raised creatine kinase level usually indicative of?
    Muscle damage. It may result from myositisis, myopathy, muscular trauma and also haemolysis.
31. What is the difference between blood urea and blood urea nitrogen (BUN)?
    Urea is a nitrogenous waste product formed in the liver from 2 molecules of ammonia as the end product of amino acid utilisation. It is then transported in the plasma to the kidneys where it is excreted in urine. BUN however, expresses the amount of nitrogen atoms in the blood incorporated to urea. In mg/100mls of plasma or serum, urea is 2.144 times higher than the magnitude of BUN.
32. List conditions which may be associated with raised urea.
    • Renal failure, renal hypoxia.
    • Chronic heart failure (with poor renal perfusion).
    • High protein diets.
    • Low carbohydrate diets (causing catabolism).
    • Dehydration.
    • Urethral obstruction.
    • Ruptured bladder.
33. What proprietary test is available to easily confirm suspected cases of renal failure by measurement of BUN?
    Azostix.
34. How might blood glucose levels be tested on whole blood?
    With the use of a glucometer, also known as a reflectance meter.
35. What are the 2 main hormones involved in the control of blood glucose levels?
    • Insulin - this increases the cellular utilisation of glucose from blood.
    • Glucagon - this causes an increased production and release of glucose from the tissues.
36. List conditions in which a raised blood glucose level may be seen.
    • Post prandial sampling.
    • Stress.
    • Cushings disease.
    • Diabetes mellitus.
    • Corticosteroid use.
    • Pancreatitis.
    • Glucose administration.
    • Morphine use.
37. List conditions in which a decreased blood glucose level may be seen.
    • Hepatic dysfunction.
    • Insulin treatment.
    • Insulinoma.
    • Starvation.
    • Malabsorption.
    • Hypothyroidism.
    • Hypoadrenocorticism.
    • Severe renal glucosuria.
    • Idiopathic in some toy breeds.
    • Artefact in an old sample.