Hematology - Levine IMHA SG

Question 1

What are the three etiologies of icterus?

Answer 1

Pre-hepatic, hepatic, and post-hepatic

Question 2

What causes spherocytosis in IMHA?

Answer 2

Primarily extravascular hemolysis - Macrophages remove a piece of the membrane from a red blood cell leaving a spherocyte

Question 3

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:

Answer 3

Immune attack at the level of bone marrow

Early disease

Question 4

What causes the RBCs to agglutinate in IMHA?

Answer 4

It is induced by five-armed IgM or large quantities of IgG – antibody induced

Question 5

What is a Coombs’ test? What reagents do you add in a Coombs’ test?

Answer 5

It is a direct antiglobulin test that detects antibodies or complement attached to the RBCs

Reagent – anti-canine IgG, IgM, and compliment

Question 6

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?

Answer 6

1. Neutrophilic leukocytosis with a left shift is termed a leukemoid response that is common in IMHA patients.
   
   1. It is due to increased marrow release during strong regenerative RBC response
   2. Leukocytosis in dogs with IMHA is correlated with tissue necrosis

Question 7

When immune destruction of platelets occurs in isolation (that is the only cell targeted), what is the disease called?

Answer 7

Immune thrombocytopenia

Question 8

Immune destruction of platelets combined with immune destruction of RBCs is called _________ ________.

Answer 8

Evan’s syndrome

Question 9

Red urine in a patient with IMHA may indicate ________ _________.

Answer 9

intravascular hemolysis

Question 10

Is there a single definitive test for IMHA?

Answer 10

No

Question 11

List some clinicopathologic changes consistent with the diagnosis of IMHA.

Answer 11

Anemia with HCT < 25% to 30%

Evidence of hemolysis

Evidence of antibodies against RBCs

Question 12

Describe when you would consider using a Coombs’ test to help you diagnose IMHA.

Answer 12

If there isn’t autoagglutination present, but there are signs of IMHA

Question 13

What are some breeds of dogs that are pre-disposed to IMHA?

Answer 13

Cocker spaniels, Old English Sheepdogs, Poodles, and Dachshunds

Question 14

IgM activates complement more efficiently than IgG, leading to ________ ________.

Answer 14

Intravascular hemolysis

Question 15

When immune-mediated disease is diagnosed, why would you consider radiographs and ultrasound?

Answer 15

To determine if the IMHA is primary or secondary

Basically, you want to rule out all secondary causes

Question 16

List some causes of hemolysis that are not immune-mediated (not primary or secondary IMHA).

Answer 16

1. Hereditary
   
   1. Pyruvate kinase (PK) deficiency
   2. Phosphofructokinase (PFK) deficiency
   3. Hereditary stomatocytosis
2. Acquired
   
   1. Toxins
   2. Hypophosphatemia
   3. Microangiopathic hemolytic anemia

Question 17

List some infectious causes that may be secondary causes of IMHA in dogs.

Answer 17

Anaplasma phagocytophilum, Babesia canis, Babesia gibsoni, Dirofilaria immitis, Leptospira, Leishmania

Question 18

List some infectious causes that may be secondary causes of IMHA in cats.

Answer 18

Cytauxzoon felis, B. felis, FIV, FIP, FeLV, and Mycoplasma haemofelis

Question 19

List some drugs that may be secondary causes of IMHA.

Answer 19

Penicillins, sulfonamides, and cephalosporins

Question 20

List some drugs that may be secondary causes of IMHA in cats.

Answer 20

Methimazole and propylthiouracil

Question 21

List a type of neoplasia that can be a secondary cause of IMHA in dogs.

Answer 21

lymphoid tumors

Question 22

List some alloimmune causes that can cause secondary IMHA in dogs and cats.

Answer 22

Dogs - transfusion reactions

Cats - neonatal hemolysis

Question 23

Describe 3 general reasons (parts of Virchow’s triad) that patients with IMHA are prone to clot formation and give an example of each.

Answer 23

Stasis of blood, vascular endothelial injury, and hypercoagulability

Question 24

What is the mortality rate of IMHA, and why do most patients with IMHA die?

Answer 24

High mortality rate – 50%

Most patients die due to pulmonary thromboembolism (PTE) and DIC

Question 25

What are the five principles of treatment in IMHA?

Answer 25

Provide supportive care

Treat tissue hypoxia

Treat secondary cause if present

Prevent hemolysis with immunosuppressive therapy

Deter formation of thrombi

Question 26

How is prednisone thought to work in the treatment of IMHA?

Answer 26

It decreases macrophage phagocytosis of anti-body coated RBCs

If given long-term, it minimizes autoantibody production by B cells

Question 27

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?

Answer 27

Consider adding a secondary immunosuppressive drug such as:

1. Azathioprine
2. Cyclosporine
3. Mycophenolate mofetil
4. Leflunomide

Question 28

What are some options to try and prevent thrombi formation in dogs with IMHA?

Answer 28

Aspirin, Clopidogrel, and Heparin

Question 29

How is it thought that aspirin (ultralow dose) works to prevent thrombi formation?

Answer 29

It inhibits platelet aggregation without inhibiting beneficial effects of prostaglandins

Question 30

What does an individualized heparin dose mean?

Answer 30

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