Red Cell Disorders

Question 1

What are the clinical signs/exam findings of patients with anemia?

Answer 1

• Clinical Signs: (severity reflects speed of disease)
  
  • Weakness, exercise intolerance
  • Poor appetite
  • Lethargy
• Physical Exam:
  
  • Pale mucous membranes
  • Tachycardia
  • Icterus with hemolysis
  • Finding specific to etiology

Question 2

How is Anemia classified as Non-regenerative or Regenerative?

Answer 2

• Red blood cell indices
• Reticulocyte count

Question 3

What findings are common in Regenerative/Pre-regenerative anemia?

Answer 3

• RBC:
  
  • spherocytes, Heinz bodies, ghost cells, MCV/MCHC
• Presence of icterus, hemoglobinuria
• PE: mass, fleas, melena

Question 4

What causes Regenerative/Pre-regenerative anemia?

Answer 4

• Hemolysis
• Blood Loss

Question 5

How is the cause of Non-regenerative anemia determined?

Answer 5

Bone marrow aspirate and core biopsy

Question 6

How is a Reticulocyte count completed

Answer 6

• Absolute Reticulocyte count: (RBC count x (Reticulocyte %/100))
  
  • Dogs >100,000 (regen)
  • Cats: Aggregates >60,000 (regen)

Question 7

Common causes of hemorrhage leading to Regenerative Anemia?

Answer 7

• Trauma
• Coagulopathy
• Neoplasia (HSA, GI tumor)
• Parasites (fleas, hookworms)

Question 8

What is the most common cause of iron-deficiency anemia?

Answer 8

Bleeding GI tumor

Question 9

Common causes of hemolysis resulting in regenerative anemia?

Answer 9

• Immune-mediated
• Parasitic/Infectious
• Toxin/Oxidative injury
• Enzyme Deficiency
• Hypophosphatemia
• Microangiopathic Disease

Question 10

What is Immune-mediated Hemolytic anemia?

Answer 10

• Primary: loss of self tolerance
  
  • Autoantibodies to cell surface antigens
  • No inciting cause identified = idiopathic
• Secondary: dysregulation of immunity
  
  • Infection, inflammation, neoplasia, drug therapy
  • Cross reacting antigen, RBC membrane damage exposes antigen or antigens attached to RBC membrane
  • Idiopathic
• Look for Underlying cause

Question 11

How is IMHA diagnosed?

Answer 11

• Regenerative anemia
  
  • 15-30% initially non-regen
• Spherocytosis
  
  • 75-90% of cases
• Autoagglutination
  
  • 60-80% of cases
• Direct antibody tests
  
  • Coomb’s test (40-80% positive)
  • RBC surface antibodies (67-100% positive)

Question 12

When is IMHA non-regenerative?

Answer 12

• Peracute IMHA
  
  • 3-4 days to mount a response
  • “re-regenerative”
• Non-regenerative IMHA
  
  • Erythroid hyperplasia
  • Erythroid maturation arrest
  • Precursor-directed Immune-mediated Anemia (PMIA)
• Pure red cell Aplasia

Question 13

What is the mortality of IMHA?

Answer 13

• 25-70% reported mortality
• <10% If live past first 2 weeks
• Pulmonary thromboembolism
• Hypoxia-related
• Multi-organ dysfunction
• Infectious complications

Question 14

How is IMHA treated?

Answer 14

• Prednisone (Prednisolone, Dexamethasone)
  
  • 2mg/kg/day or 60mg/M²/day
  • First line therapy
  • Inhibits uptake of antibody-coated RBCs
  • Only treatment most dogs will need
  • response in 3-5 days
  • Does not affect anibody production
    
    • insufficient for intravascular iMHA
    • Insufficient for autoagglutination
• Cyclosporine
  
  • first drug added
  • minimal toxicity
• Azathioprine
  
  • Myelosuppressive
  • least expensive, slower onset
• Leflunomide
• Mycophenolate mofetil

Question 15

What are the adjunct therapies for IMHA (with autoagglutination)?

Answer 15

• Heprin therapy
  
  • in hospital
• Clopidogrel (Plavix) or Aspirin therapy
  
  • ULDA is questionably effective
• Rivaroxaban (Xarelto)
  
  • 0.9mg/kg/day
  • Factor Xa inhibitor

Question 16

What parasites cause hemolysis?

Answer 16

• Babesia gibsoni (pitbull)
• Babesia canis (greyhound)
• Mycoplasma hemofelis
• Mycoplasma hemocanis
  
  • uncommon

Question 17

What are some other common causes of hemolysis?

Answer 17

• Zinc
  
  • skin outments
  • pennies (>1893)
  • metalic items
• Others
  
  • Onions/garlic
  • Acetaminophen
  • Benzocaine spray
  • Skunk

Question 18

What is Phosphofructokinase (PFK) deficiency?

Answer 18

• Exacerbated by pantin, barking, etc
• Intermittent hemoglobinuria
• DNA testing available
  
  • most commonly affects English springer spaniels

Question 19

What is Pyuvate Kinase (PK) deficiency

Answer 19

• Myelofibrosis and osteosclerosis
• Hemosiderosis with hepatic failure at <5 yo
• Common in Basenjis, beagles, others

Question 20

What is Hypophosphatemia?

Answer 20

• P < 2.5 mg/dL
• Deplete ATP ⇢ ⇡osmotic fragility and oxidative injury
• Etiology: Diabetic ketoacidosis, refeeding syndrome

Question 21

What is Microangiopathy?

Answer 21

• Cell fragmentation - schistocytes
• Etiology:
  
  • Heartworm disease, hemagiosarcoma, DIC

Question 22

What is a Histiosarcoma?

Answer 22

• Variable presentations
• Hemolytic anemia, Thrombocytopenia
• Poor response to chemotherapy

Question 23

What causes hemolytic anemias in cats?

Answer 23

• Drug reactions
• FeLV, FIV, FIP
• Mycoplasma hemofelis
• Cytauxzoonosis
• Primary IMHA

Question 24

What are the common causes of Non-regenerative Anemia?

Answer 24

• Decreased Production:
  
  • Systemic disease
    
    • Anemia of chronic disease
    • Chronic kidney disease ⇣EPO
    • Hypothyroidism
  • Bone Marrow disease
    
    • Neoplasia
    • Myelofibrosis/myelodysplasia/pure red cell aplasia/aplastic
    • Immune mediated

Question 25

What are the causes of Myelofibrosis in Dogs?

Answer 25

• Primary (idiopathic)
  
  • Rare
  • Atypical precursors, bone marrow fibrosis
• Secondary
  
  • Toxic insult, IMHA, neoplasia, drug tx,
  • Short survival time with malignancy

Question 26

How is Myelofibrosis treated?

Answer 26

• Immunosuppressive therapy (~60% success)
• Erythropoietin therapy (variable success

Question 27

Common causes of non-regenerative anemia in cats?

Answer 27

• Chonic renal failure
• FeLV, FIV infections
• immune - Pure Red Cell Aplasia
• Myelodysplastic syndromes
• Dugs
• Idiopathic