JR Clinical haematology Flashcards
What is the main stimulus for red blood cell production?
Erythropoeitin
What is erythropoeisis?
Production of RBCs
What is an immature RBC/RBC precursor called?
Reticulocyte
What type do you collect samples for haematology in?
EDTA
Where are platelets most likely to be found in a blood smear?
Feathered edge
Where are leukocytes more likely to be found in a blood smear?
On the lateral edges
What is anisocytosis?
Variation in cell size
What is polychromasia?
Variation in cell colour
What colour are immature RBCs?
More purple/blue
What size are immature RBCs?
Larger
What can cause macrocytosis in RBCs?
Regeneration
FeLV if not changed colour
What can cause microcytosis/hypochromasia in RBCs?
Iron deficiency
When are RBCs nucleated?
Very immature erythroblasts - regeneration
Or birds and reptiles
What are schistocytes?
RBC fragments - from shear injury
What can cause schistocytes?
Splenic tumour
What does poikilocytosis mean?
Abnormal RBC shape
What are acanthocytes?
RBCs with large blunt ended projections
What are keratocytes?
RBCs with cup shape missing
What are blister cells?
RBCs with a blister on the surface
What are echinocytes?
Crenated RBCs, thin projections
What are spherocytes?
RBCs with no central pallor - no lighter centre where the concave shape is
What are produced in oxidative injury of RBCs?
Heinz bodies
What are codocytes?
RBCs that look like targets
What are inclusion bodies?
Blobs in RBCs that are got from diseases
What does anaemia mean?
Reduction in RBC mass
What is erythrocytosis?
Increased concentration of erythrocytes/RBCs
What is relative erythrocytosis?
Erythrocytosis due to reduced blood volume
What is absolute erythrocytosis?
Erythrocytosis due to a genuine increase in RBC mass
How does the body identify anaemia?
In the kidney
What is the normal PCV of a dog?
35-55%
What is a regenerative anaemia?
Body is still making more RBCs to correct the anaemia
What are the two main causes of regenerative anaemias?
Haemolysis
Haemorrhage
What is non-regenerative anaemia?
Body isnt producing any RBCs
What are the two main causes of non-regenerative anaemia?
Primary bone marrow disease
Extra-bone marrow disease
What are the two type of reticulocyte?
Punctate reticulocytes
Aggregate reticulocytes
What are the less mature type of reticulocyte?
Aggregate reticulocytes
What do aggregate reticulocytes look like?
Have large amounts of RNA in them - can be stained
What do punctate reticulocytes look like?
Small dots of RNA in them
What are punctate reticulocytes found in?
Only in cats
What are morphological features of regeneration?
Polychromasia
Anisocytosis
Nucleated RBCs
What does MCV mean in a blood test?
Size of blood cells - mean cell volume
What does MCH/C mean in a blood test?
Mean cell haemoglobin/concentration
Mean volume of haemoglobin
What are the different levels of MCV?
Normocytic - normal
Macro/microcytic - bigger or smaller
What are the different levels of MCH/C?
Hypochromic - indicates less haemoglobin
Where does normal extracellular haemolysis occur?
Mainly in the spleen
What causes normal extracellular haemolysis?
Phagocytosis of RBCs
What causes normal intracellular haemolysis?
RBC lysis due to membrane damage
What are some differentials for haemolysis?
Immune mediated haemolytic anaemia
Parasites
Oxidative damage
Neonatal isoerythrolysis
What parasite is most common in cats for causing haemolysis?
Mycoplasma haemofelis
What causes primary immune mediated haemolytic anaemia?
Autoimmune disease
What causes secondary immune mediated haemolytic anaemia?
Neoplastic or inflammatory disease
Drugs
What is molecular mimicry?
Pathogenic protein looks similar to a protein on host RBC
What is a hapten?
A drug binds to surface of a RBC, immune system attacks hapten and local damage as well
What is a coombs test?
Evaluates for the presence of antibody or complement on the RBC surface
When do cats get neonatal isoerythrolysis?
When type A/AB kitted ingest colostrum from a type B (strong anti-A alloantibodies) queen
What are the two main causes of haemorrhage?
Coagulopathy - bleeding disorder
Primary pathology
What is the most common non traumatic primary pathology for haemorrhage?
Ruptured splenic malignancy
What are signs of haemorrhage in GI tract?
Haematemesis
Haematochezia
What is haematemesis?
Blood in vomit
What is haematochezia?
Fresh blood in faeces
What is the most common cause of primary coagulopathy?
Thrombocytopaenia - low platelet count
What is the most common causes of respiratory tract haemorrhage?
Angiostrongylus vasorum
Rodenticide intoxication
What does a blood smear exam look like for non-regenerative anaemias?
Normocytic, normochromic
What is an extra bone marrow disease that causes non regenerative anaemia?
Chronic disease (eg. inflammatory) which impedes normal bone marrow function
What are some causes of primary bone marrow disease?
Leukaemia - infiltrates bone marrow
Non-regen IMHA - immune system attacks bone marrow
What can be a normal cause of absolute erythrocytosis?
Certain breeds
Splenic contraction
Hyperthyroidism
How does erythrocytosis present?
Increase in blood viscosity
What can cause absolute erythrocytosis?
Altitude
Pulmonary disease
Right-left cardiac shunt - blood not going to lungs
Neoplastic proliferation of RBCs in the bone marrow
What is another word of absolute erythrocytosis?
Polycythaemia
How do you find the total WBC count from a blood smear?
Count all WBCs in 10 fields
Calculate mean then x1.5
What is the circulating and marginating pool of neutrophils?
Circulating - in centre of vessels
Marginating - roll along edge
What are immature neutrophils called?
Band cells - not segmented nuclei yet
What is left shift?
Neutrophils get more immature
What are the two types of left shift?
Regenerative
Non-regenerative
What is regenerative left shift?
Left shift with neutrophilia - high neutrophils
What is non-regenerative left shift?
Left shift with normal or reduced neutrophil count - demand too high for body to keep up
What is toxic change to neutrophils?
Where the neutrophils start to look different
What cause toxic change to neutrophils?
Overwhelming demand for neutrophils
What can cause mild neutrophilia?
Stress
Steroids
What can cause severe neutrophilia?
Inflammation
Pyrexia
etc.
What is the word for reduced neutrophils?
Neutropenia
What can cause neutropenia?
Sampling error - marginating Overwhelming demand Reduced production - drugs, infections etc. Breed Immune mediated destruction
What is a precursor of a macrophage?
Monocyte
What is the role of monocytes in immune response?
Antigen presentation
Cytokine production
Phagocytosis
What is the function of eosinophils?
Parasite defence
Allergic responses
When is eosinophilia commonly seen?
As part of a stress leukogram
Where are lymphocytes produced?
Peripheral lymphoid tissues
What can cause lymphocytosis?
Age - young
Adrenaline
Mobilisation, increased demand
Leukaemia
What can cause lymphopenia?
Decreased production - immunodeficiency
Redistribution - stress
What does a stress leukogram look like?
Increase WBC count Increased neutrophils Decreased lymphocytes increased monocytes decreased eosinophils
What is the dominant WBC type in cats/dogs/horses?
Neutrophils
What is the dominant WBC type in cattle?
Lymphocytes
What is haemostasis?
The process of preventing/stopping haemorrhage
What is primary haemostasis?
Forming the platelet plug
What is exposed to form the platelet plug?
Von Willebrand factor
What clotting factors are involved in the intrinsic pathway?
Factor 8, 9, 11, 12
What clotting factors are involved in the extrinsic pathway?
Tissue factor-VII complex
What clotting factors are involved in the common clotting pathway?
2 (thrombin), 10, fibrinogen and fibrin
What are the 3 pathways of the clotting cascade?
Intrinsic, extrinsic and common pathways
What is tertiary haemostasis?
Fibrinolysis
What do primary haemostatic disorders present as?
Petechial haemorrhages
Mucosal bleeds
What are the 3 causes of primary haemostatic disorders?
Platelet disorders - thrombocytopenia
Von Willebrand disease
Vasculopathies - disease of blood vessels
What are the two different types of thrombocytopenia?
Immune mediated
Consumptive level
What does immune mediated thrombocytopenia present as?
Usually absolute - no platelets as immune system is very thorough
What is consumptive level thrombocytopenia?
Platelets used up in lots of clots due to chronic disseminated intravascular coagulation
What does consumptive level thrombocytopenia present as?
Above 30x10^9 platelets - some platelets still left
Which breed of dog has altered platelets? What are they called?
King Charles Cavaliers - macroplatelets
How many platelets cause spontaneous haemorrhage?
<30x10^9/L
How many platelets cause induced haemorrhage?
<50x10^9/L
What are some causes of secondary immune mediated thrombocytopenia?
Infection eg. lepto, ehrlichia
Inflammatory/neoplastic systemic disease
Drug/toxin exposure
What is the most common cause of consumptive level thrombocytopenia?
Angiostrongylus vasorum
What can be a cause of primary coagulopathy without any thrombocytopenia?
von Willebrand disease
ThrombocytoPATHia
What do secondary haemostatic disorders usually present as?
Major cavity bleeds
What causes secondary haemostatic disorders?
Clotting factor deficiency
What can cause clotting factor deficiencies?
Rodenticide intoxication
Angiostrongylus vasorum
Liver disease
Congenital - haemophilia
What test do you do to evaluate the extrinsic pathway of the clotting cascade?
PT - prothrombin time
What test do you do to evaluate the intrinsic pathway of the clotting cascade?
APTT - activated partial thromboplastin time
What does a prolonged PT suggest?
Extrinsic pathway problem, factor VII deficiency
Or early combined deficiency
What is the main cause for extrinsic pathway problems?
Rodenticide intoxication
What does rodenticide intoxication cause?
Vitamin K inactivation/deficiency so cant make factors 2,7,9 or 10
What does a prolonged aPTT suggest?
Intrinsic pathway problem - factors 8,9,11,12 deficiency
What can cause intrinsic pathway problems?
Haemophilia
Liver failure
Angiostrongylus vasorum
DIC
What is DIC?
Disseminated intravascular coagulation - loss of clotting equilibrium, so consumes clotting factors in lots of little clots
What can cause both a prolonged PT and aPTT?
Vitamin K inactivation - rodenticide intoxication Severe cholestasis Liver failure Angiostrongylus vasorum DIC
