PATHOLOGY - Small Animal Anaemia Flashcards
What is anaemia?
Anaemia is the reduction in haemaglobin concentration in the blood
What is erythropoiesis?
Erythropoiesis is the process by which erthythropoietic stem cells develop into mature erythrocytes
Describe the physiological regulation of erythropoiesis
Decreased oxygen delivery to the kidneys stimulates the production and secretion of the erythropoietin (EPO) into the bloodstream to stimulate erythropoiesis
Which three components are required for haemaglobin production?
Iron
Vitamin B12 and folate
Functional bone marrow
What are the clinical signs of acute anaemia?
Tachycardia
Tachypnoea
Hyperpnoea
Pale mucous membranes
Bounding or weak pulses
Hypotension
What are the clinical signs of chronic anaemia?
Lethargy
Weakness
Exercise intolerance
Anorexia
Pale mucous membranes
What are the three main classifications of anaemia?
Non-regenerative anaemia
Regenerative anaemia
Pre-regenerative anaemia
What is pre-regenerative anaemia?
Pre-regenerative anaemia is when reticulocytes and other indicators of regeneration are not seen in the blood, but there has not been sufficient time for them to appear
What is non-regenerative anaemia?
Non-regenerative anaemia is where the bone marrow does not have an adequate response to decreased erythrocytes
What are the two main causes of non-regenative anaemia?
Primary bone marrow disease
Secondary failure of erythropoiesis
What are the distinguising clinical signs of anaemia caused by primary bone marrow disease?
Lethargy
Weakness
Exercise intolerance
Relatively bright alert responsive for degree of anaemia
Other cell lines may be affected (e.g. thrombocytopenia)
Clinical signs relate to a gradual reduction in O2 carrying capacity
List seven examples of primary bone marrow diseases
Aplastic anaemia
Red cell aplasia
Pancytopenia
Myelofibrosis
Bone marrow infiltration
Myelodysplastic syndrome
Precursor immune-mediated haemolytic anaemia
What is aplastic anaemia?
Aplastic anaemia is the immune mediated destruction of hematopoietic stem cells
What is red cell aplasia?
Red cell aplasia is the immune mediated destruction of erythrocyte progenitor cells
What is pancytopenia?
Pancytopenia is when there is a deficiency in all three celllular components of blood (erythrocytes, leukocytes, thrombocytes)
Caused by aplastic anaemia
What is myelofibrosis?
Myelofibrosis is a neoplastic disease where bone marrow is infiltrated and replaced with fibrotic tissue
What is myelodysplastic syndrome?
Myelodysplastic syndrome is a neoplastic condition in which hematopoietic stem cells do not correctly develop into mature blood cells
Which species is myelodysplastic syndrome more commonly seen in?
Cats as myelodysplastic syndrome can be caused by feline leukaemia virus (FeLV)
What is precursor immune-mediated haemolytic anaemia?
Precursor immune-mediated haemolytic anaemia is immune-mediated destruction of erythrocyte precursors within the bone marrow
List five examples of causes of secondary failure of erythropoiesis
Anaemia of inflammatory disease
Chronic renal disease
Endocrine disease
Haemaglobin synthesis defects (e.g. iron deficiency)
Nuclear maturation defects (e.g. cobalamin also known as vitamin B12 deficiency)
How does inflammatory disease cause secondary failure of erythropoiesis?
Inflammation triggers cytokine release and cytokines can prevent the release of intracellular iron which will prevent haemoglobin production
This is to prevent bacteria deriving energy from oxidising iron
How does chronic kidney disease cause secondary failure of erythropoiesis?
Chronic kidney disease will impair erythropoietin secretion into the bloodstream to trigger erythropoiesis
What are some of the clinical signs you would see in anaemia secondary to chronic renal disease?
Clinical signs of chronic anaemia
Polyuria
Polydipsia
Vomiting
Decreased appetite
Weight loss
i.e. signs of chronic renal disease
Give an example of an endocrine disease that causes secondary failure of erythropoiesis
Hypothyroidism
How does hypothyroidism cause secondary failure of erythropoiesis?
Hypothyroidism causes decreased thyroid hormone production which causes depression of bone marrow activity, iron deficiency and vitamin B12 and folate deficiency
What are some of the clinical signs you would see in anaemia secondary to hypothyroidism?
Clinical signs of chronic anaemia
Dermatological disease
i.e. signs of hypothyroidism
What are the main causes of iron deficiency anaemia?
Chronic external bleeding or internal gastrointestinal bleeding
Which further testing should you do to investigate iron deficiency anaemia?
Parastite screening
Ultrasound to investigate for lesions
What is regenerative anaemia?
Regenerative anaemia is where the bone marrow responds to a decrease in erythrocytes through producing more erythrocytes and prematurely releases immature erythrocytes
What are the two main forms of regenerative anaemia?
Haemolytic anaemia
Haemorrhagic anaemia
What are the distinguising clinical signs of haemolytic anaemia?
Jaundice
Haemaglobinuria
Hepato-splenomegaly
Pyrexia if there is an infectious aetiology
What are the two forms of haemolysis?
Extravascular haemolysis
Intravasvular haemolysis
What is extravascular haemolysis?
Extravascular haemolysis is where erythrocytes are engulfed by macrophages in the spleen and liver
What is intravascular haemolysis?
Intavascular haemolysis is where erythrocytes are bound to by complement and lysed by the membrane attack complex (MAC), which is a series perforin proteins which forms pores in the erythrocyte membrane causing haemolysis