Flashcards in Abnormalities of the Erythron Deck (60)
What do RBCs look like?
Biconcave disc shape in most species giving an area of central-pallor and a high surface area to volume ratio and allows for deformability
What shape RBCs do camelids have?
How do bird and reptile's RBCs differ?
They are nucleated
What do RBCs contain?
Haemoglobin as their function is oxygen transport
What are the production sites of RBCs?
Liver/spleen in the foetus and then swaps to bone marrow in neonates
In growing mammals bone marrow of all bones produces RBCs in adults only femur/humerus and flat bones do
Which organs become activated in increased demand for RBCs?
Liver, spleen and long bone bone marrow
What are the production requirement for RBCs?
Stem cells, space in marrow, growth factors (IL-3, GM-CSF, G-CSF erythropoietin), iron, cholesterol/lipids for membrane, enzyme pathways for construction and maintenance
How do RBCs mature?
Series of cells types starting with lots of cytoplasm and a large nucleus which gradually condenses and finally disappears
What is the lifespan of RBCs?
100 days in dogs, 70 days in cats and 150 days in cattle and horses
How are RBCs removed from the circulation?
Phagocytic macrophages taking up senescent red cells and recycling components or intravascular haemolysis
What is the definition of anaemia?
Reduction in red cell mass evidenced by a decreased haemoglobin concentration, packed cell volume, haematocrit or red blood cell concentration
What is a haematocrit?
Gives same information as PCV but is calculated by a machine so relies on red cell count and volume and is less accurate
What is the red blood cell concentration (RBC)?
Total number of red blood cells
What is the haemoglobin (Hgb)?
Total oxygen carrying capacity
What is the PCV?
Percentage of red cells in a volume of blood through a manual technique that also allows buffy coat assessment, plasma and total protein measurement
What causes a decreased red cell mass?
Increased loss too large or fast for compensation
Decreased production with losses not matched by production
What are the different ways of classifying anaemia?
By severity, by haemoglobin concentration, by red cell measurements or regenerative/non-regenerative
What are the characteristics of mild anaemia?
From just below normal PCV to 10% below normal PCV, may not affect animal until exercised, common in animals with long standing disease/endocrine disorders
What are the characteristics of moderate anaemia?
Varies between species depending on normal PCV for each, animals may show weakness or be well adapted but only if chronic, mucous membrane pallor and fast bounding pulse
What are the characteristics of severe anaemia?
PCV in lower teens downwards, pale, weak, unable to exercise, may need oxygen before diagnostic procedures, don't fight with very anaemic cats
How is anaemia classified by haemoglobin concentration?
Either normochromic or hypochromic can't be hyper
MCHC/MCH measured on panel
Due to decreased iron/poor iron incorporation
How are red cell measurements classified?
Normocytic, microcytic or macrocytic
What are the characteristics of normocytic anaemia?
Erythrocytes of unremarkable size often associated with mild non-regenerative anaemia or acute haemorrhage
What causes microcytic anaemia?
Red cell haemoglobin concentration determines when division stops so iron deficiency allows one more division resulting in a smaller cell with same haemoglobin concentration as a normal cell
PSS/iron deficiency/hepatic failure or Akitas
What causes macrocytic anaemia?
In regeneration seen as polychromatophils
Some poodles have them
Generally young cells
FeLV cats/myelodysplasia/artefact of stored blood
How does regenerative anaemia occur?
Fall in oxygenation detected by kidneys which release erythropoietin which activates the bone arrow and takes 2-3 days for cells to appear in circulation
What is the indicator of regenerative anaemia?
How are reticulocytes detected?
Diff-Quick or Giemsa stain look larger, bluer cells called polychromatophils
New Methylene Blue precipitates RNA forming aggregates/reticulum = reticulocytes
How do reticulocytes differ in cats?
Retics released as aggregate retics and mature to punctate retics over time
Counts should record either aggregate or both