Approach to Anaemia

Question 1

Define Anaemia

Answer 1

A CLINICAL sign associated with an underlying disease where there is a reduction of RBC mass

Question 2

How to we detect anaeamia?

Answer 2

By values being below the Reference Interval for any of:

1. PCV/ Hct (packed cell vol and haematocrit is the same thing = % blood volume filled by erythrocytes
2. RBC count
3. Total Hb

Question 3

What are 3 causes of anaemia?

and how to the RBC appear in these cases?

Answer 3

1. Inadequate production RBC by bone marrow = non regenerative.
   RBC = normally normocytic and normchromic (size, shape, colour)
2. Increased destruction = regenerative = RBC
   typically macrocytic hypochromic = BIG, pale/blue RBC and see lots of reticulocytes (immature)
3. haemorrhage =
   typically microcytic, hypochromic = smale, pale. Not regenerative enough
   also see hypoproteinaemia = low levels of protein in boiochem

Question 4

What are 3 of the bodys responses to anaemia?

Answer 4

1. 2-3 diphosphoglycerate (2,3-DPG) increases in erythrocytes which lowers the oxygen haemoglobin affinity = better O2 delivery
2. Behavioural responses = exercise intolerent, sleep
3. Increase EPO - erythropoietin hormone which drives erythropoiesis

Question 5

Clinical signs often seen

Answer 5

– 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

Question 6

Diagnostic tests and why

Answer 6

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?

Question 7

How do we classify anaemia?

Answer 7

1. Degree of severity
2. Erythrocyte indexes
3. Regenerative Response

Question 8

How do we assess severity of anaemia?

Answer 8

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)

Question 9

What are erythrocyte indexes?

Answer 9

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

Question 10

Waht does acute haemorrhage result in?

Answer 10

HYPOvolarmic shock NOT anaemia becuase

proportional loss of all blood components

Question 11

How does animal recover from acute haemorrhgae?

Answer 11

interstitial fluid moves into the vascular space (within few hours)
– blood ‘dilution’  both erythrocyte mass (PCV/Hct/RBC) and total protein fall

Question 12

Clinical signs acute ahemorrhage

Answer 12

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

Question 13

Following haemorrhage, interstitial fluid moves into vascular space.What happens to PCV and TP

Answer 13

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

Question 14

Acute haemorrhage results in what?
How does the animal recover??
What does this recovery do?

Answer 14

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

Question 15

When can acute haemorrhage result in death?

Answer 15

Loss of less than 30% total blood volume

Question 16

Hypovolaemic shock clinical signs

Answer 16

–	Pallor
–	Tachycardia
–	Weak peripheral pulses
–	Poor peripheral perfusion
•	increased Capillary Refill Time
•	cold extremities
•	increased lactate

Question 17

What is chronic blood loss

Answer 17

Bleeding for over 2 weeks

Question 18

What can chronic blood loss lead to?

Answer 18

• 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

Question 19

What type of anaemai could chronic blood loss cause?

Answer 19

May be regenerative or non-regenerative! eventually depletion of iron will slow down erythropoiesis (iron is essential for erythropoiesis) becoming less regenerative over time

Question 20

What are the identifiable hallmarks of regeneration of anaemia on a blood smear?

Answer 20

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

Question 21

What is more sensitive measure? reticulocytosis or polychromasia?

Answer 21

Reticulocytosis is more sensitive/ accurate than polychromasia!
(All polychromatophils are reticulocytes, but not all reticulocytes are polychromatophils)