Laboratory Diagnostic Aids Flashcards
What is polychromasia ?
Differing intensity of staining
What is crenation?
Cells showing spiky margins due to shrinkage. Air drying of blood film too slow.
What are Howell Jolly bodies?
These are basophilic nuclear remnants seen in erythrocytes. Due to anaemia and splenic disorders.
What is Roleaux formation?
Arrangement of red blood cells into stacks. Associated with fibrinogen or globulin increase in blood. Normal in horses but not cats or dogs.
What are reticulocytes?
Immature red blood cells with nucleus. IMHA, blood loss.
What is anisocytosis?
Different size rbcs. Anaemia is cause.
What increases PCV
Dehydration, diabetes insipidus.
What decreases PCV
Anaemia, bleeding, hypovolaemic shock
What causes Eosinophilia
Parasitic infestation
Allergy
What causes eosinopenia
Steroid usage
Cushings disease
What causes neutrophilia
Inflammation, infection, stress, steroids
What is hemolysis
Disintegration of the red blood cells due to trauma, contact with certain chemicals or osmotic changes.
Causes of hemolysis?
Too small needle used
Shaking of sample
Pulling on the syringe plunger too hard
Blood in contact with acid, alkali or alcohol
Effects of hemolysis on a blood sample
Abnormally low rbc and pcv
abnormally high protein level
What is lipaemia
Presence of lipids in the blood.
Usually from a feed prior to venepuncture.
Effects of lipaemia on blood sample
Elevated biochem values
increased likelihood of haemolysis
Serum vs plasma
Plasma contains clotting factor fibrinogen
What is PCV
Packed Cell Volume - percentage of red blood cells in the blood. Also referred as haematocrit.
What is normal dog and cat pcv
Dog 37-55%
Cat 30-45%
Why is EDTA used for PCV ?
EDTA removes calcium needed for clotting. Heparin interferes with activation and formation of thrombin and delays clotting.
3 examples of Romanowsky stain
- Diffquik
- Giemsa
- Leishman’s
What stains are used in Romanowsky staining
Methylene blue
Eosin red
What is polychromasia - hipochromasia?
Polychromasia - differing intensity of staining of rbc
Hipochromasia - understaining
What is Improved Neubauer Haemocytometer?
For counting of WBCs
Increased protein level reasons
Dehydration, lactation, infection, neoplasia
Decreased protein levels reasons
Hepatic/renal dysfunction, malabsorption, immunodeficiency
Raised cholesterol levels
Hypothyroidism, cushings disease, post prandial, diabetes mellitus.
Raised urea reasons
Renal failure, renal hypoxia, chronic heart failure, high protein diets, low carb diets, dehydration, urethral obstruction, ruptured bladder.
What is pink/red, EDTA tube is used for
Haematology
What is orange Lit/Hep tube used for
Biochemistry
What is white/brown serum tube used for
All serum tests
What is green sodium citrate tube used for
Coagulation studies/prothrombin test
What is yellow sodium fluoride/potassium oxalate tube used for
Glucose testing
4 types of casts
Hyaline, granular, cellular, waxy
What cellular casts can indicate?
Acute renal disease
What granular casts can indicate?
Chronic renal disease. Associated with inflammatory change.
What is the name of the counting chamber used to count worm ova?
The McMaster slide or Ovassay
What worm eggs cannot be counted with McMaster or Ovassay and why
Tapeworm ova as they sink, while roundworms float.
