Introduction to Erythron Flashcards
What is the difference between the shape of RBC in most mammals compared to birds, reptiles and camelids?
Mammals - biconcave, anucleated, central pallor
Birds/reptiles - nucleated
Camelids- Elliptical
What are the RBC production sites in
a) Foetus
b) Adult
a) Foetus - Liver/spleen
b) Adult - bone marrow (L/S maintain erythropoietic capacity) - long bones
What is the erythrocyte lifespan of
a) Dog
b) Cat
c) horse/cattle
a) 100 d
b) 70 d
c) 150 d
What are the routes of RBC removal?
Major route - senescent RC by phagocytic macrophages
Minor route - intravascular haemolysis
Components of a CBC
RBC concentration Total hemoglobin (HGB) hematocrit (HCT) and spun PCV Mean cell volume (MCV) Mean cell hemoglobin (MCH) Mean cell hemoglobin concentration (MCHC) Red cell distribution width (RDW Platelet numbers Total WBC Breakdown of numbers of each type of WBC
What is anaemia and how can you find evidence of it in the CBC?
Reduction of Red cell mass
- Haemoglobin conc
- PCV
- Haematocrit
- Red blood cell conc
Polychromasia
Red blood cells that vary in color (some may be normal, some pale, etc)
Anisocytosis
the presence of red blood cells of unequal size
What are the classifications of anaemia?
- Mild, moderate, severe
- Regen or non-regen
- Normocytic, microcytic, macrocytic
- Normochromic, hypochromic (hyperchromic)
Hypochromasia
Erythrocytes that do not take up as much stain as usual (caused by decreased hemoglobin?)
Macrocytosis
the presence of macrocytes (large RBCs) in the blood
Normocytic
a) what are the abnormal terms?
Erythrocytes of unremarkable size
seen in: mild non-regen anaemia, acute haemorrhage
a) Microcytic and macrocytic
Why does microcytic erythrocytes occur?
Examples
Red cell haemoglobin conc determines when division stops - iron deficiency allows one more division = SMALLER RC
eg. PSS, Fe deficiency, hepatic failure
Name a normal breed that you can see microcytic red blood cells
Akitas
What is macrocytic erythrocytes and when would you see them?
In regeneration
- polychromatophils - larger than mature RBCs
What breed would you see macrocytic red blood cells?
Poodles
What is regenerative anaemia in response to?
Reduction in oxygenation
- Kidneys respond to low O2 by releasing erythropoietin
- stimulates bone marrow to increase red cell production
- takes 2-3 days and young red cells increase in circulation
What are young red blood cells called?
Reticulocytes
Polychromatophils and reticulocytes
SAME CELLS - have ribosomal RNA
What stain would you use to see reticulocytes?
Diff-Quik or Giemsa stained smear
ribosomal RNA - larger bluer cells (polychromatophils)
New methylene blue - RNA precipitates forming aggregates
What disease in cats can you see Macrocytosis?
FeLV
What is the normal PCV for a dog and a cat?
Dog: 45%
Cat: 35%
What is the normal amount of reticulocytes in a dog and a cat?
Dog - 1% corrected
Cat - 0.4%
What happens in regenerative anaemia to the reticulocyte %
Dog >1% corrected
Cat >0.4%
What are the 2 reasons for increased loss in Regenerative anaemia?
Haemolysis Haemorrhage (internal and external)
What are some examples of haemorrhage?
External: Melena Urinary tract epistaxis Post trauma/surgery
Internal: Bleeding tumours Trauma Into tissue (bleeding diathesis - tendency) surgery
What are some examples of haemolysis?
- intravascular or extravascular
- immune mediated - test with Coombs test = anti-RBC antibody
- damaged/abnormal RBC
Agglutination vs. Rouleaux
Agglutination will appear as irregularly clumped together RBCs. Rouleaux will appear as rows of clumped RBCs (artefactual change)
What can you see in intravascular haemolysis like Immune mediated haemolytic anaemia?
Ghost cells
What are Ghost cells?
Erythrocyte membrane that has remained intact following hemolysis - lost haemoglobin
What can you see in extravascular anaemia like IMHA?
Spherocytes
What are spherocytes?
Half eaten RBC - don’t have central pallors (abnormal phagocytosis)
What lab diagnostics can you find in IMHA?
Blood smear:
- Opsonised RBCs
- Lysed or phagocytosed RBCs (lysed is more common with IgM)
- May agglutinate
- Ghost cells
Increased bilirubin (esp extravascular H)
Neutrophilia, monocytosis
Platelets affected?
What is the Evan’s syndrome?
IMHA + immune mediated platelet destruction (thrombocytopenia)
Signs of regeneration
Howell-Joly bodies, polychromasia, nucleated RBCs, anisocytosis
Howell-Jolly bodies
histopathological findings of basophilic nuclear remnants (clusters of DNA) in circulating erythrocytes
What parasites cause haemolysis?
Mycoplasma haemofelis
-Blood-borne, epicellular parasites; come in large and small forms. Parasite increases fragility and hemolysis of RBCs. Cyclical in nature (3-8 weeks)
DDX: PCR
Babesia
Name a type of haemolysis with damaged red blood cells
Heinz body associated anaemia
What are Heinz bodies and how are they formed?
Denatured haemoglobin in RBC
Formed from oxidative injury
Causes of heinz bodies
Oxidative injury: Onions (dogs, cattle) Paracetamol (aspirin) Propofol (cats) Vitamin K Diabetes mellitus (cats) Hyperthyroidism (cats) Brassica (cattle) Red maple (horses) Propylene glycol
What are eccentroycytes?
Haemoglobin has uneven distribution within cell
Cause of eccentrocytosis
Oxidative damage, causes membrane cross bonding due to damage of membrane skeletal proteins
Signs of oxidative damage
Heinz bodies, eccentrocytes, pyknocytes
What are the Shear injury products and how are they formed?
Keratocytes, schistocytes, acanthocytes
Microangiopathic damage (tumors with narrow vessels), or organ inflammatory beds where there is fibrin stranding (severe hepatitis, DIC).
Acanthocytes
Erythrocytes with non-uniform, varying projections from their membranes, common in hemangiosarcomas
Schistocytes
Red cell fragments that occur secondary to shear injury
Associated with fibrin deposition in vessels and DIC
Most common causes of non-regenerative anemia
- Anaemia of inflammatory/chronic disease -Chronic renal failure
- Decreased production in marrow
- HypoT4 and Hyperadrenocorticism
- FeLV
Name some examples why anaemia occurs in inflamm/chronic disease
Fe sequestration - storage in macrophages not in circulation
inflamm mediators
shortened erythrocyte survival
Why does chronic renal failure cause non-regen anaemia?
Kidneys produce erythropoietin - less production
Why does HypoT4 and Hyperadrenocorticism cause anaemia?
Thyroid hormone and cortisol impact on red cell production
What is aplastic anaemia?
all precursors wiped out
Myelodysplasia
abnormal production of blood cells = ineffective erythropoiesis
Lead to leukaemia
Myelopthisis
Neoplasia altering environment in bone marrow
Basophilic stippling
erythrocytes display small dots at the periphery
Leptocyte
An abnormally thin or flattened red blood cell having a central rounded pigmented area, a middle pigmentless zone, and a pigmented edge
What is erythrocytosis?
Polycythemia
increase in HCT, RBC count and haemoglobin
- dehydration (volume contraction)
- RBC redistribution (splenic contraction
Left shift neutrophils
Neutrophils that exhibit foamy cytoplasm and basophilia, as a result of being produced too quickly (toxic insult)
Regenerative left shift
neutrophilia
segemented > bands
Degenerative left shift
Neutropenia
Bands > segmented
Right shift neutrophils
Hypersegmented nucleus, very unhappy cell
What is a normal finding in puppies?
Low haematocrit
Low total protein vs adults
What are normal findings in Cavalier king Charles spaniel?
Lower platelet numbers
Larger platelets
What are the normal findings in sight hounds?
Higher haematocrit
lower neutrophils
vacuolated eosinophils
Poikilocytosis
Abnormally shaped red blood cells
Which species do you commonly see Rouleaux RBC?
Feline and Equine
Which species do platelets stain poorly?
Equine
Which species exhibits more anisocytosis of RBC than other species?
Bovine
