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Function of RBCs?

- haemaglobin oxygen carrying capacity


Where are RBCs produced in foetus? In adult?

- liver/spleen in foetus
- bone marrow in neonate
- growing animals = BM of all bones
- red marrow/yellow marrow (femur/humerus) in long bones, flat bones remain active
- liver and spleen maintain erythropoietic capacity, espcially if incresed demand (extramedullary haematopoeisis) as do long bones (reversion to red marrow)


Production requirements for haemopoeisis?

- stem cells
- space in marrow
- Growth factors (IL3, GM-CSF, G-CSF, erythropoeitin)
- Iron
- Cholesterol/lipids for membrane (more humans)
- enzyme pathways for construction and maintainance


Outline the different cell lines as a RBC matures

- Rubriblast (nucleoli, fine granules in nucleus, dark blue cytoplasm)
- Prorubriocyte
- Basophilicrubricyte
- Polychromatophilic rubricyte
- Metarubricyte
- Reticulocyte


What is blue basic dye attracted to?



How long do RBCs live for?

- 100d (Dog)
- 70d cat
- 150d horse and cattle


How are RBCs removed when too old normally?

- MAJOR ROUTE: macrophage phagocytoses recycles components
- MINOR ROUTE: intravascular haemolysis


What is anaemia? Howo may this be appreciated diagnostically?

> reduction in red cell mass, evidence in decreased:
- [Hgb] conc Haemoglobin
- PCV packed cell volume
- HCT haematocrit
- [RBC] RBC conc


How should PCV, HCT, [Hbg] nd [RBC] values change?

All together - if they change independantly suspect something


What is HCT?

Haematocrit (= PCV)
- calculated by machine
- Relies on RBC count and cell volume (less accurate)


What is [RBC]]

- total red cell numbers


What is [Hbg]?

- total oxygen carrying capacity


What is PCV?

- packed cell volume = % red cells in a volume of blood
- centrifuged whole blood, red cells red as % of column length


What else can be assessed in PCV?

- buffy coat assessment (WBC)
- plasma (clear/straw or pink if hamolysed)
- total protein measurement (put serum into refractometer)
> if bleeding, losing protein, protein v


Different classifications of anaemia?

> mild/mod/severe
> regenerative/non-regenerative
> normocytic/microcytic/macrocytic
> normochromic/hypochromic (hyperchromic artefact)
- Haemoglobin
* helps to narrow the cause of anaemia *


Define mild anaemia

- normal - 10% decrease PCV
- may not affect animal until excercised
- common in animals with ongstanding dz, endocrine disorders etc.
- will not present for this as main presenting factor


Define moderate anameia

- varies between species, depends on normal PCV of each
- weakness or may be well adapted (takes time)
- mm pallor
- fast bounding pulse


DDefine severe anameia

- PCV low teens and less
- pale, weak, unable to excercise
- may need O2 stabilisation before dxx
> dont fight with severely anaemic cats!


How would hypochromic anaemia appear? Why?

- increased central pallor
- MCHC/MCH (hbg conc)
- decreased in iron deficiency/poor iron incorporation (with microcytosis)


When does hyperchromia occour?

Artefact, cells cannot be hyperchromic
- haemolysis


What is the MCV?

= mean cell volume
- average volume of a single red cell (micro/normo/macrocytic)


Distinguishing features of normocytic

- erythrocytes unremarkable size
- often assoc with mild, non-regnerative anaemia, acute haemmorrhage etc.


Distinguishing features of microcytic?

- RBC haemoglobin conc determines when devision stops
- iron deficiency allows oe more division -> smaller RBC
- eg. seen with PSS, Fe deficiency, hepatic failure
- akitas (congenital, normal cells but smaller, NOT path)


Distinguishing features of macrocytic?

- in regeneration
- polychromatophils larger than mature RBC
- more purple colour too
- we want these as indicate regenerationi (yay)
- some poodles inherited dz (path)


How may macrocytosis affect your dxx?

Can increase PCV as dependant on size of cell as well as number


When is macrocytosis also seen?

- FeLV affected cats
- myelodysplasia
- common artefact in stored (usually posted) blood


What is regenerative anaemia and what stimulates it?

- body response to a fall in oxygenation
- kidneys release EPO -> BM stimulation
- takes 2-3d and younger red cells (polychromatophils/reticulocytes) increase in circulation.


Non regeneratvie

no notes


What are the 2 Ddx for regenerative anaemia?

- haemorrhage (loss)
- haemolysis (destroyed)
> if you can control the loss, animal will get better by itself
> allows assessmeent of how well an anmal is resposing


What cells do you look for as hallmarks of regenerative anaemia?

> reticulocytes
- RNA precipitates
- new methylene blue
- aggregates/reticulum forms
> polychromatophils
- Diff-Quick/Giemsa
- young immature cells containing ribosomal RNA show as large, blue cells (polychromatophils)
> these are the SAME CELLS


How do cat reticulocytes differ?

- cat retics released as aggregate retics, mature to punctate retics over time
- retic counts should record AGGREGATE or BOTH (punctates hang around for a while)


How can regenerative v non-regenerative be distignusihed?

- reticulocyte % (1000 red cells counted, retics expressed as %)
- corected % (same no retics will take up more % in a very anaemic animal)
> retic% x patient PCV/normal PCV
[ PCV 45% normal dog, 35% normal cat ]
> regenerative if >1% corrected (Dog) or >0.4% (cat)
> absolute reticulocyte conc may be better ([RBC] x Retic%)


What casues decreased red cell mass?

- ^ loss or v production


Causes of increased losses of RBC

> haemorrhage (external)
- melena
- UT
- epistaxis
- post-trauma/surgery


Shape of RBCs = ? Reason? Exceptions?

- biconcave disk in most species
- central pallor (seenin dogs)
- high surface area to volume ratio -> ^ deformability
> camelids have elliptical RBCs
> anucleate in all animals except birds and reptiles