Immune Diseases - IMHA

Question 1

Age predisposition of IMHA of both dogs and cats

Answer 1

Dogs - Middle aged; 6.5yrs avg (13wks-13yrs)
Cats - Young/middle aged; 3yrs (6mths-9yrs)
Any age can be affected

Question 2

Breed disposition of IMHA

Answer 2

Dogs - 1/3 of all cases are Cocker Spaniels (also Springer, Poodles, OESDs etc.)
Cats - no predispositions

Question 3

Gender predisposition of IMHA

Answer 3

Dogs - Female

Cats - Male

Question 4

How does vaccination influence IMHA

Answer 4

25% of dogs had been vaccinated within days of diagnosis in one study

Question 5

IMHA seasonal incidence?

Answer 5

Spring and summer

Question 6

Infectious (secondary) causes of RBC destruction in IMHA include

Answer 6

1) Tick-bourne diseases
2) Babesia spp.
3) Dirofilaria immitis
4) Microfilaria

Question 7

Toxic (secondary) causes of RBC destruction in IMHA include

Answer 7

1) Zinc
2) Acetaminophen
3) Onions/garlic
4) Copper
5) Castor beans

Question 8

Drug related (secondary) causes of RBC destruction in IMHA include

Answer 8

Penicillin, Cephalosporins, Sulfonamides, Quinidine, Procainamide, Phenothiazines, Methylene blue, Methimazole

Question 9

Neoplastic (secondary) causes of RBC destruction in IMHA include

Answer 9

Hemolymphatic tumors and Solid tumors

Question 10

Immune (secondary) causes of RBC destruction in IMHA include

Answer 10

SLE and hypothyroidism

Question 11

Metabolic (secondary) causes of RBC destruction in IMHA include

Answer 11

Hypophophataemia (severe)

Question 12

Inherited / intrinsic RBC defects in IMHA include

Answer 12

PFK deficiency and PK deficiency

Question 13

Explain the pathophysiology of IMHA

Answer 13

Increase in procoagulant activity, decrease in anticoagulant activity, decreased fibrinolysis = Thromboembolism, DIC

Question 14

Mucous membranes physical exam findings in IMHA

Answer 14

Pale
+/- icteric
+/- petechia/ecchymoses

Question 15

Temperature physical exam findings in IMHA

Answer 15

Dogs - Pyrexia

Cats - Hypothermia

Question 16

Pulse physical exam findings in IMHA

Answer 16

Tachycardia
+/- prominent pulses
+/- anemic murmur

Question 17

Respiratory physical exam findings in IMHA

Answer 17

Tachypnea

+/- respiratory distress

Question 18

Abdominal palpation physical exam findings in IMHA

Answer 18

Hepatosplenomegly and Abdominal pain

Question 19

IMHA most common clinical signs

Answer 19

Lethargy, depression, anorexia

Question 20

IMHA less common clinical signs

Answer 20

Vomiting & Diarrhea
PU/PD
Weakness
Exercise Intolerence
Collapse/ syncope
Pigmenturia
Respiratory distress
Pica

Question 21

CBC results for IMHA

Answer 21

Moderate to severe regenerative anemia
Neutrophilic leukocytosis
Thrombocytopenia
Normal TP (rules out blood loss)
Evidence of RBC destruction (spherocytosis, autoagglutionation, +ve Coomb's test)

Question 22

Describe Saline/ slide agglutination test

Answer 22

1 drop blood + 1-2 drops saline
Agitate gently (rock back & forth)
Check for both micro and macroscopic agglutination
+ve in 40-89% IMHA dogs

Question 23

Biochemistry results for IMHA

Answer 23

Increase Tbilirubin, ALT

+/- azotemia

Question 24

Urinanalysis results for IMHA

Answer 24

Bilirubinuria

+/- hemoglobinuria

Question 25

Imaging results for IMHA

Answer 25

To rule out secondary causes
Thoracic Radio: patchy alveolar opacities, pronounced interstitial pattern, mid pleural effusion (PTE)
Abdominal Ultra: Hepatosplenomegaly, extramedullary hematopoiesis

Question 26

Bone marrow aspirate / biopsy for IMHA

Answer 26

Non regenerative anemia

Question 27

Coagulation parameters for IMHA

Answer 27

If DIC present; Increase ACT, PT/PTT etc.

Other test Thromboelastography

Question 28

Treatment for IMHA

Answer 28

Immunosuppression, reduce risk of thrombosis with anticoagulants and antiplatelet drugs, doxycyline and supportive care

Question 29

1st line steroids (immunosuppression) for treatment of IMHA

Answer 29

Prednisone (2-4mg/kg/day) PO

Dexamethasone SQ or IV if can’t tolerate PO medications

Question 30

2nd line steroids (immunosuppression) for treatment of IMHA

Answer 30

Azathioprine, Cyclosporine, Mycophenolate mofetil

Question 31

Anticoagulants (antithrombotics) used for the treatment of IMHA

Answer 31

Unfractured heparin (UFH) IV or SQ
Low molecular weight heparin (LMWH) SQ
Coumadin/warfarin PO
Require monitoring

Question 32

Antiplatelet drugs (antithrombotics) used for the treatment of IMHA

Answer 32

Aspirin
Clopidogrel
Doesn’t require monitoring

Question 33

Supportive treatment for IMHA

Answer 33

Blood transfusion (in severely anemic patients if hemodynamically unstable, required in 70-90% of dogs, PRBCs preferred)
Oxygen therapy
IVF therapy
GI protectants (Antacids - H2 blocker/ proton pump inhibitor/ PG analogue; Sucralfate)

Question 34

Long term management of IMHA

Answer 34

History, PE, and CBC once to twice until resolution of anemia
Biweekly until tappering of immunosuppressive medications is initiated
Maintenance of immunosuppressive glucocorticoid dose until Hct is stable or rising followed by 25-50% dosage reduction every 2-4wks (withdrawal 3-6mths)
CBC prior to each dosage reduction

Question 35

Complications in IMHA

Answer 35

Pulmonary thromboembolism (PTE)
- most common cause of death in IMHA dogs

Question 36

IMHA prognosis

Answer 36

Guarded
Dogs - 26-70% mortality; highest in first two weeks after diagnosis. May die suddenly even if anemia has resolved or relapse during treatment.
Cats - 24% mortality

Question 37

Favorable criteria for IMHA

Answer 37

Response to treatment (rise in Hct within 3-7days)

Response to transfusion

Question 38

Unfavorable criteria for IMHA

Answer 38

Persistent agglutination despite immunosuppression drug
Thrombocytopenia
Leukocytosis +/- left shift
Use of cyclophosphamide

Question 39

IMHA vaccine

Answer 39

None