Approach to Anaemia Flashcards
(30 cards)
Define Anaemia
A CLINICAL sign associated with an underlying disease where there is a reduction of RBC mass
How to we detect anaeamia?
By values being below the Reference Interval for any of:
- PCV/ Hct (packed cell vol and haematocrit is the same thing = % blood volume filled by erythrocytes
- RBC count
- Total Hb
What are 3 causes of anaemia?
and how to the RBC appear in these cases?
- Inadequate production RBC by bone marrow = non regenerative.
RBC = normally normocytic and normchromic (size, shape, colour) - Increased destruction = regenerative = RBC
typically macrocytic hypochromic = BIG, pale/blue RBC and see lots of reticulocytes (immature) - haemorrhage =
typically microcytic, hypochromic = smale, pale. Not regenerative enough
also see hypoproteinaemia = low levels of protein in boiochem
What are 3 of the bodys responses to anaemia?
- 2-3 diphosphoglycerate (2,3-DPG) increases in erythrocytes which lowers the oxygen haemoglobin affinity = better O2 delivery
- Behavioural responses = exercise intolerent, sleep
- Increase EPO - erythropoietin hormone which drives erythropoiesis
Clinical signs often seen
– Pallor
– Weakness
– Exercise intolerance
– Tachycardia
– Tachypnoea
– ‘Haemic’ murmur - inc turbulence blood
– Other depending on the cause of the anaemia
Icterus = jaundice
Petechiation = if immune mediated disease can have IM haemolytic anaemia AND IM thrombocytopnea
Evidence of bleeding -melina, epistasis, bruising.
Spleen v important in Anaemic
Diagnostic tests and why
Laboratory tests:
1. full haemogram- reticulocyte count to assess if regen or not
total protein, albumin,globulin, biochemistry, urinalysis.
Reticulocyte count = used to decide whether anaemia is regenerative or not
Coagulation test
Saline agglutination/Coombs’ test espec if suspect IM haemolytic
Diagnostic Imaging especially if older as underlying health
Evidence of bleeding, splenomegaly, or concurrent diseases?
Faecal = GI haemorrhage?
How do we classify anaemia?
- Degree of severity
- Erythrocyte indexes
- Regenerative Response
How do we assess severity of anaemia?
PCV/ HCT (packed cell volume/ haematocrit)
Normal = 35-50%
• Mild (30-36% in dogs, 20-24% in cats)
• Moderate (18-29% in dogs, 15-19% in cats)
• Severe (<18% in dogs, <15% in cats)
What are erythrocyte indexes?
MCV = mean corpuscular volume MCHC = mean corpuscular hemoglobin concentration
- Microcytic / normocytic / macrocytic
- Big, normal, small
- Hypochromic / normochromic
- Indication of regeneration and iron deficiency
- Look at reticulocyte count to identify if regenerative or not as caused by different things to non regenerative
Waht does acute haemorrhage result in?
HYPOvolarmic shock NOT anaemia becuase
proportional loss of all blood components
How does animal recover from acute haemorrhgae?
interstitial fluid moves into the vascular space (within few hours)
– blood ‘dilution’ both erythrocyte mass (PCV/Hct/RBC) and total protein fall
Clinical signs acute ahemorrhage
hypovolaemic shock especially if acute:
– Pallor
– Tachycardia
– Weak peripheral pulses
– Poor peripheral perfusion
• increased Capillary Refill Time
• cold extremities
• increased lactate
• Single incident of acute haemorrhage <30%
– Unlikely to result in significant anaemia
– PCV may go down but you will be ok
• Loss of more >30% of blood volume often fatal
• Very unlikely for anaemic to be cause of significant consequence of acute haemorrhage/ main problem
Following haemorrhage, interstitial fluid moves into vascular space.What happens to PCV and TP
Both fall but someitmes PCV can inc due to splenic contraction. But everything lost in proportion = once hypovolaemia is resolved, PCV goes down but normally manageable level for patient
Acute haemorrhage results in what?
How does the animal recover??
What does this recovery do?
HYPovolaemic shock. NOT anaemia.
Due to proportional loss of all blood components
Animal pale and v vasoconstricted
Animal recovers as ISF moves into vascular space.
REcovery measn that blood is “diluted” = PCV/ Hct and RBC and TP fall which happens after 2ish hrs
When can acute haemorrhage result in death?
Loss of less than 30% total blood volume
Hypovolaemic shock clinical signs
– Pallor
– Tachycardia
– Weak peripheral pulses
– Poor peripheral perfusion
* increased Capillary Refill Time
* cold extremities
* increased lactate
What is chronic blood loss
Bleeding for over 2 weeks
What can chronic blood loss lead to?
• May lead to consumption of iron stores and iron deficiency anaemia (IDA)
- Iron stores are abundant in adults so it takes about > 1month of continued bleeding for IDA to develop
What type of anaemai could chronic blood loss cause?
May be regenerative or non-regenerative! eventually depletion of iron will slow down erythropoiesis (iron is essential for erythropoiesis) becoming less regenerative over time
What are the identifiable hallmarks of regeneration of anaemia on a blood smear?
polychromasia - red blood cells show up as bluish-gray when they are stained with a particular type of dye. This happens when red blood cells are immature because they were released too early from your bone marrow.
Reticulocytosis - increase in reticulocytes, immature red blood cells
What is more sensitive measure? reticulocytosis or polychromasia?
Reticulocytosis is more sensitive/ accurate than polychromasia!
(All polychromatophils are reticulocytes, but not all reticulocytes are polychromatophils)
Feline reticulocytes
Little bit more complicated than dogs as cats have 2 forms of reticulocytes .
1. Aggregate reticulocytes – what look like when released from BM, last 24 hrs. Larger take up more stain.
Overtime loose these, becoming punctate = smaller staining material within, last up to 10
Could have been circulating for a few days.
Which is why count based on aggregate reticulocytes count = what BM is actually doing at this point
Following acute haemorrhage what does blood results look like?
- immediately following haemorrhage all blood components are lost in proportion so PCV normal. Maybe slightly higher if splenic contraction.
- PCV and TP fall after 24 hrs if ongoing losses as interstitial fluid moved into vasculature to increase circulating volume, decreasing the conc
When would haemorrhage result in anaemia?
if lost more than 30% circulating volume. all would present as hypovolaemic shock, but only really anaemic if greater 30%
