Anaemia Flashcards
Define anaemia
Clinical presentation defined by reduction in PCV, red blood cell count, haemoglobin
Give examples of normal variations that may lead to increased PCV
- Greyhounds and other sighthounds often naturally have higher PCV (>50)
- Stress/excitement causing splenic contraction, temporary increase in circulating RBCs
- Anabolic steroids
Give examples of normal variations that may lead to decreased PCV
- Age: puppies and kittens <6-12 months have lower normal range
- ACP (relaxes splenic capsule)
- Reproductive status (late pregnancy)
What are teh potential aetiologies of anaemia?
Loss of blood cells via blood loss, reduced production or haemolysis
What are the potential causes of a regenerative anaemia?
- Haemorrhage
- Haemolysis
List potential causes of haemorrhage
- Internal loss or external loss
- Trauma
- Coagulopathy
- Endo or ectoparasites
- GI blood loss (tumours, ulcers)
List the potential causes of haemolysis
- Erythrocytes removed from circulation by macrophages in spleen, liver, bone marrow (extravascular haemolysis) because they or the system are abnormal
- Destruction of erythrocytes in vascular space
- Immune mediated diseases
- Infection
- Oxidative damage
- Rare genetic disorders
Give examples of infections that lead to haemolysis
- Babesia spp..
- Mycoplasma haemofelis
Give examples pf oxidants that lead to haemolysis
- Heavy metals
- Onion
- Garlic
- rape
- Kale
Cabbages - Drugs e.g. paracetamol
- Phenothiazine in horses
Compare the toxic dose of paracetamol in cats and dogs
- Cats: much lower, 10-40mg/kg
- Dogs: 100mg/kg
Explain how oxidants cause haemolysis
Oxidation of haem iron to form methaemoglobin and/or oxidation of haemoglobin to form Heinz bodies
List genetic disorders that may cause haemolysis
- Hereditary non-spherocytic haemolytic anaemia
- Pyruvate kinase deficiency
- Phosphodructokinase deficiency
- Feline porphyra
- Haemolysis in Abyssinian and Somali cats
List potential causes for intra-marrow suppression of erythropoiesis leading to non-regenerative anaemia
- Primary disorders of erythropoiesis
- iron deficiency
- Aplastic anaemia (damage to haemopoietic stem cells)
- Pure red cell aplasia (only red cells not produced)
- Myelofirbosis
- Myelodysplastic syndromes
Describe myelofibrosis
- Scarring in bone marrow, can no longer produce cells
- Replacement of marrow with fibroblasts and collagen
- May be primary or secondary following IMHA, neoplasia for example
What may cause aplastic anaemia?
- Ehrlichia canis
- Canine and feline parvo
- Idiopathic
- Drugs incl. chemo
Describe pure red cell aplasia
- Only red cells not produced
- Can be immune mediated, FeLV-C
Describe myelodusplastic syndromes
- Stem cells not forming properly, usually some form of neoplasia
- Includes Refractory Anaemia (RA), Refractory Anaemia with Excess Blasts (RAEB) and others
- Slow form of leukaemia
List potential causes for extra-marrow suppression of erythropoiesis leading to non-regenerative anaemia
- Anaemia of chronic disease
- Anaemia of chronic renal failure
- Secondary to endocrine disorders
- Oestrogen induced bone marrow suppression
- FeLV (additionally to specific disease of FeLV - C)
(secondary disorder of erythropoiesis)
What type of anaemia are the following blood smear features indicative of?
- reticulocytes >5%
- Anisocytosis
- Poikilocytosis
- Normoblastosis
- Howell-Jolly bodies elevated
- Heinz bodies elevated
- Reactive leukocytoosis
Regenerative anaemia
Describe the blood smear characteristics of non-regnerative anaemia
- No atempt to produce new cells
- No reticulocites/polychromasia, anisocytosis, poikilocytosis, normoblastosis (unless damage to bone marrow stroma or in MPD), Howell-Jolly bodies, Heinz bodies or reactive leukocytosis
- I..e normocytic, normochromic cells
What is a potential consequence of longstanding chronic bleeding?
Iron deficiency anaemia
What conditions are indicated by macrocytic, normochronic red blood cells?
- FeLV
- Myeloproliferative disease
- Vit B12 and folic acid deficiency
- Chemotherapy e.g. with methotrexate
Compare the clinical signs of acute and chronic anaemia
Often absent in chronic due to adaptation
Describe the clinical signs of anaemia
- Pale mucous membranes
- Lethargy, exercise intolerance
- Tachypnoea, tachycardia (lack of oxygen dist.)
- Poor pulse quality
- Flow murmur
- Pica (esp. mineral based material)
- +/- signs related to underlying pathology e.g. splenomegaly, lymphadenopathy, pain, icterus, melaena
What does icterus suggest in anaemia?
Haemolysis
What are the main differentials for anaemia?
- Cardiovascular disease
- Liver disease
List clinical signs that may indicate haemolysis
- Haemoglobinuria
- Haemoglobinaemia
- Icterus (seen earlier in serum vs mucous membranes/sclera)
How would you interpret an acute haemorrhage with smear showing it as non-regenerative?
Probably not non-regenerative, regenerative response lags 2-4 days behind anaemia
How would you interpret a cause of severe anaemia with mild clinical signs?
Suggests chronic disease, and increased O2 carrying capacity of the remaining RBCs
Identify tests that are useful in the investigation of anaemia
- Haematology
- Herum biochem
- Urinalysis
- Virology
- Faecal analysis
- Coomb’s test
- Coagulation profile
- Imaging
- Bone marrow biopsy
- Microhaematocrit
Discuss the use of PCV in the investigation of anaemia
- May have operator error
- Patient side Hb testing is an alternative
- Interpret with total solids
- Acute blood loss may not result in changes in PCV or total solids for some hours
What may high total solids indicate and how does this relate to anaemia?
Indicates dehydration, can mask severity of anaemia
What do normal total solids in relation to anaemia indicate?
Non-regenerative anaemia or haemolysis
What do low total solids in relation to anaemia indicate?
Blood loss
What do the following values indicate regarding the severity of anaemia (and from that, the most likely underlying cause):
- PCV (%): 15
- RBCC (x10^12/l): 2.0
- Hb (g/dl): 4.5
Severe
Suggests: haemolysis, bone marrow disease
What do the following values indicate regarding the severity of anaemia:
- PCV (%): 23
- RBCC (x10^12/l): 3.5
- Hb (g/dl): 7.5
Moderate
What do the following values indicate regarding the severity of anaemia (and from that, most likely cause):
- PCV (%): 30
- RBCC (x10^12/l): 4.8
- Hb (g/dl): 10.0
Mild: anaemia of chronic disease, acute blood loss
What are the aims of management of severe anaemia?
- Reduce oxygen expenditure
- Increase oxygen carrying capacity
- Allow time to diagnose and address cause of anaemia
What are the consequences of >20% blood volume loss?
Peripheral vasoconstriction, tachycardia
What are the consequences of >30-40% blood volume loss?
Decreased cardiac output, hypotension, collapse
What are the consequences of >50% blood volume loss?
Shock and death
Outline the management of acute haemorrhage
- Prevent further bleeding: look for source, apply pressure
- Fluid replacement
- Blood transfusion support
- Treatment of underlying disorder
What is most significant to address in acute haemorrhage?
Immediate effects of volume depletion, loss of circulating RBCs can be sorted out later
Describe the clinical signs of Mycoplasma haemofelis
- Variable related to haemolytic anaemia
- Regenreative anaemia
- Jaundice
- Pale mucous membranes
- Pyrexia, depression, weakness, anorexia, weight loss
- Severity varies from mild to fatal
Which groups of cats are more severely affected by Mycoplasma haemofelis?
Young or immunosuppressed (FIV)
How is Mycoplasma haemofelis transmitted?
Fleas, ticks, and vertically
How is Mycoplasma haemofelis diagnosed?
- Blood smear with Romanowsky or acridine orange stain sampled when cat is sick and before treatment
- Quantitative PCR
What is the main disadvantage of diagnosing Mycoplasma haemofelis based on blood smears?
Cyclical parasitaemia on red blood cells means they may be missed (false negatives)
Describe the treatment of Mycoplasma haemofelis
- Doxycycline first choice (10mg/kg SID) before or with food
- Enrofloxacin second choice (5mg/kg SID)
- Treat for 2-8 weeks
- Repeat PCR (cure rather than remission may be difficult)
- Supportive treatment e.g. transfusion may be necessary
Describe the occurence of Babeisa in UK dogs
- Not endemic to UK, but sporadic cases in travelling dogs
- Tick borne
- Endemic in cattle
Describe the presentation of Babesia
Signs of haemolytic anaemia
Describe the presentation of Ehrlichia canis
- Acute phase: malaise and bleeding, difficult to identify
- Chronic: complete bone marrow failure, intra marrow non-regenerative anaemia, white cell problems
Outline the prevention of Babesia and Ehrlichia
- Both tick transmission, avoid tick habitats, check dogs daily and use acaricides
- Vaccine for Babesia available, prevents severe disease but not infection
Outline the treatment for oxidant anaemia
- Immediate removal of oxidative agent (emesis <4hr)
- Activated charcoal
- Supportive care
- Monitor haematological parameters, may need transufsion
- For paracetamol: acetyl cysteine (dogs and cats) and ascorbic acid (cats only) reverse oxidate effects
How do acetyl cysteine and ascorbic acid work in the treatment of paracetamol intoxication?
- Acetyl cysteine increases elimination of toxic metabolites
- Ascorbic acid resolves methaemoglobinaemia by returning to oxyhaemoglobin
How does copper poisoning occur?
Capacity for Cu storage in liver exceeded, sudden release of Cu stores into circulation, leading to haemolysis and liver damage (icterus)
Give examples of sheep feeds high in copper
- Silage where pig or chicken manure has been used
- Brewer’s mash from copper stills
Describe the clinical signs of copper poisoning in sheep
- Lethargy, anaemia, teeth grinding, polydipsia
- Pale, icteric MMs, haemoglobinuria
- Death 1-2 days after onset of signs
- At PM, tissues pale to dark yellow, kidneys very dark
Outline the treatment and prognosis of copper poisoning in sheep
- Oral or injectable ammonoium tetrathiomolybdate
- Addition of copper binders to feed e.g. sulphur
- Expensive
- Poor prognosis if severe
Identify the potential aetiologies of iron deficiency anaemia
- Late feature of chronic blood loss
- Bone marrow stores deplete before anaemia develops
describe the diagnosis of iron deficiency anaemia
- Normo to microcytic, hypochromic
- Non-regenerative
- Increased platelet count
- Red cells fragile, schistocytes, keratocytes and target cells seen
Outline the treatment of iron deficiency anaemia
Long term treatment required to replenish bone marrow
Outline how anaemia of chronic disease occurs and the treatment
- Generally mild, non-regenerative anaemia
- Bone marrow responds less well to EPO
- Reduced iron stores, reduced RBC survival
- Endocrine disorders
- Need to treat the underlying condition
Outline how oestrogen induced bone marrow suppression occurs and leads to anaemia
- Persistent oestrus in ferrets
- Oestrogen damages haemopoietic stem cells
Outline how anaemia of chronic kidney disease occurs and outline the treatment
- Reduced renal EPO production
- Check for other sources of blood loss e.g. GI ulcers which can also occur with kidney disease
- Treat with recombinant human EPO (becomes less effective in cats over time due to antibody production, expensive)
