Page 1378 - Small Animal Internal Medicine, 6th Edition

1350 PART XIII Hematology

exogenous corticosteroids may result in decreased antibody phosphate (1-2 mg/kg). I also advocate the use of prophylac-
binding to the surface of the RBCs. tic heparin and/or aspirin therapy because dogs with hemo-
VetBooks.ir to 2-4 mg/kg of prednisone q12-24h) constitute the treat- lysis are at high risk for DIC and thrombosis. I use heparin
Immunosuppressive doses of corticosteroids (equivalent
therapy, 50 to 75 IU/kg subcutaneously (SC) q8h, and/or
ment of choice for primary IHA. Although dexamethasone
can be used initially, it should not be used as maintenance minidose aspirin, 0.5 mg/kg PO q24h. These dosages of
heparin usually do not result in therapy-related prolongation
therapy for prolonged periods because of its higher potential of the activated clotting time (ACT) or activated partial
to cause GI tract ulceration or pancreatitis; in addition, if
given on an alternate-day basis, it causes interference with
the hypothalamic-pituitary-adrenal axis. In equivalent doses, Prednisone
dexamethasone does not appear to be more beneficial than 30 800
prednisone in dogs. In cats with IHA, I use dexamethasone Cytoxan
(4-5 mg/cat PO q1-2 wk) instead of prednisolone, with a Transfusion
high degree of success. 600
A high percentage of dogs treated with corticoster- 20
oids show a marked improvement within 24 to 96 hours
(Fig. 82.7). Corticosteroids mainly act by three different 400
mechanisms—they suppress MPS activity, decrease comple- PCV (%) Platelets (×1000/µL)
ment and antibody binding to the cells, and suppress Ig
production. The first two effects are rapid in onset (hours), 10
whereas the third effect is delayed (1-3 weeks). For addi- 200
tional information, see Chapters 72 and 73.
I have seen a high number of dogs with acute or peracute
IHA generally associated with icterus and autoagglutination 0 0
that undergo rapid deterioration and usually die of throm- 0 2 4 6 8
boembolism of the liver, lungs, or kidneys despite aggressive Day
corticosteroid therapy (Fig. 82.8). In those patients, I use FIG 82.7
cyclophosphamide (Cytoxan), 200 to 300 mg/m PO or IV Response to treatment in a dog with immune hemolytic
2
in a single dose over a 5- to 10-minute period, or human IV anemia (IHA) and immune-mediated thrombocytopenia
immunoglobulin (IVIG), 0.5 g/kg as an IV infusion, in con- (Evans syndrome). PCV, Packed cell volume; –•–, PCV;
junction with a single IV dose of dexamethasone sodium –Δ–, platelets; ↓, treatment administered.

L L

A B

FIG 82.8
Thoracic radiographs before (A) and after anticoagulant therapy (B) in a mixed-breed
dog with immune hemolytic anemia (IHA). Notice the almost complete consolidation of the
left pulmonary field (A) and resolution 72 hours after treatment with heparin and aspirin
(B).