Hematology - Levine IMHA SG Flashcards
What are the three etiologies of icterus?
Pre-hepatic, hepatic, and post-hepatic
What causes spherocytosis in IMHA?
Primarily extravascular hemolysis - Macrophages remove a piece of the membrane from a red blood cell leaving a spherocyte
You have a patient with anemia, spherocytes, and autoagglutation. You are sure that dog has IMHA, but her anemia is non-regenerative. List two reasons why her anemia could be nonregenerative:
Immune attack at the level of bone marrow
Early disease
What causes the RBCs to agglutinate in IMHA?
It is induced by five-armed IgM or large quantities of IgG – antibody induced
What is a Coombs’ test? What reagents do you add in a Coombs’ test?
It is a direct antiglobulin test that detects antibodies or complement attached to the RBCs
Reagent – anti-canine IgG, IgM, and compliment
Your colleague has a Cocker Spaniel patient with regenerative anemia, spherocytosis, and icterus. The dog also has 60,000 neutrophils/ml and 4,000 monocytes/ml. She is worried that the dog has an infection because of this high WBC count and asks you what type of infection you think that she has. What do you tell her about her dog’s leukocytosis?
- Neutrophilic leukocytosis with a left shift is termed a leukemoid response that is common in IMHA patients.
- It is due to increased marrow release during strong regenerative RBC response
- Leukocytosis in dogs with IMHA is correlated with tissue necrosis
When immune destruction of platelets occurs in isolation (that is the only cell targeted), what is the disease called?
Immune thrombocytopenia
Immune destruction of platelets combined with immune destruction of RBCs is called _________ ________.
Evan’s syndrome
Red urine in a patient with IMHA may indicate ________ _________.
intravascular hemolysis
Is there a single definitive test for IMHA?
No
List some clinicopathologic changes consistent with the diagnosis of IMHA.
Anemia with HCT < 25% to 30%
Evidence of hemolysis
Evidence of antibodies against RBCs
Describe when you would consider using a Coombs’ test to help you diagnose IMHA.
If there isn’t autoagglutination present, but there are signs of IMHA
What are some breeds of dogs that are pre-disposed to IMHA?
Cocker spaniels, Old English Sheepdogs, Poodles, and Dachshunds
IgM activates complement more efficiently than IgG, leading to ________ ________.
Intravascular hemolysis
When immune-mediated disease is diagnosed, why would you consider radiographs and ultrasound?
To determine if the IMHA is primary or secondary
Basically, you want to rule out all secondary causes
List some causes of hemolysis that are not immune-mediated (not primary or secondary IMHA).
- Hereditary
- Pyruvate kinase (PK) deficiency
- Phosphofructokinase (PFK) deficiency
- Hereditary stomatocytosis
- Acquired
- Toxins
- Hypophosphatemia
- Microangiopathic hemolytic anemia
List some infectious causes that may be secondary causes of IMHA in dogs.
Anaplasma phagocytophilum, Babesia canis, Babesia gibsoni, Dirofilaria immitis, Leptospira, Leishmania
List some infectious causes that may be secondary causes of IMHA in cats.
Cytauxzoon felis, B. felis, FIV, FIP, FeLV, and Mycoplasma haemofelis
List some drugs that may be secondary causes of IMHA.
Penicillins, sulfonamides, and cephalosporins
List some drugs that may be secondary causes of IMHA in cats.
Methimazole and propylthiouracil
List a type of neoplasia that can be a secondary cause of IMHA in dogs.
lymphoid tumors
List some alloimmune causes that can cause secondary IMHA in dogs and cats.
Dogs - transfusion reactions
Cats - neonatal hemolysis
Describe 3 general reasons (parts of Virchow’s triad) that patients with IMHA are prone to clot formation and give an example of each.
Stasis of blood, vascular endothelial injury, and hypercoagulability
What is the mortality rate of IMHA, and why do most patients with IMHA die?
High mortality rate – 50%
Most patients die due to pulmonary thromboembolism (PTE) and DIC
What are the five principles of treatment in IMHA?
Provide supportive care
Treat tissue hypoxia
Treat secondary cause if present
Prevent hemolysis with immunosuppressive therapy
Deter formation of thrombi
How is prednisone thought to work in the treatment of IMHA?
It decreases macrophage phagocytosis of anti-body coated RBCs
If given long-term, it minimizes autoantibody production by B cells
Fluffy is your first IMHA patient. You supported her through her terrible anemia with pRBC transfusions and immunosuppressive prednisone therapy. She went home last week doing great. Her mom calls you today and complains about her panting, drinking tons, needing to go outside all the time, and begging constantly for food. Fluffy is driving her crazy. What might you consider doing with her treatment plan in order to get her off of her steroids more quickly?
Consider adding a secondary immunosuppressive drug such as:
- Azathioprine
- Cyclosporine
- Mycophenolate mofetil
- Leflunomide
What are some options to try and prevent thrombi formation in dogs with IMHA?
Aspirin, Clopidogrel, and Heparin
How is it thought that aspirin (ultralow dose) works to prevent thrombi formation?
It inhibits platelet aggregation without inhibiting beneficial effects of prostaglandins
What does an individualized heparin dose mean?
Dose it to the individual patient in order to get the target aPTT that you want – 1.5 to 2x normal
Every patient is different – if you don’t monitor it in the patient then don’t give it
