Comparison of platelet count recovery with use of vincristine and prednisone or prednisone alone for treatment for severe immune-mediated thrombocytopenia in dogs.
OBJECTIVE
To evaluate the effect of prednisone alone, compared with a combination of prednisone and vincristine, on platelet counts in bleeding dogs with severe primary immune-mediated thrombocytopenia (IMT).


METHODS
Prospective case study.


METHODS
24 dogs with severe primary IMT PROCEDURE: All dogs received immunosuppressive doses of prednisone (1.5 to 2 mg/kg [0.7 to 0.9 mg/lb] of body weight, PO, q 12 h). In addition, 12 dogs received a single dose of vincristine (0.02 mg/kg [0.01 mg/lb], IV). Platelet count, transfusion requirement, and outcome were monitored. A response was defined as an increase in platelet count to > or = 40,000/microl. Dogs in the prednisone group that failed to respond received 1 dose of vincristine on day 7.


RESULTS
Dogs that received prednisone and vincristine had a significantly faster increase in platelet count to > or = 40,000 platelets/microl than dogs that received prednisone alone (mean +/- SD, 4.9 +/- 1.1 vs 6.8 +/- 4.5 days, respectively). A similarly rapid response was observed in dogs that received vincristine on day 7 after treatment with prednisone alone failed. Furthermore, duration of hospitalization was reduced in the vincristine group, compared with the prednisone group (5.4 +/- 0.3 vs 7.3 +/- 0.5 days, respectively). No adverse effects attributable to vincristine were observed in any dog.


CONCLUSIONS
Administration of combined vincristine and prednisone is associated with more rapid increase in platelet numbers and shortened duration of hospitalization in dogs with IMT, compared with use of prednisone alone. Early use of vincristine seems warranted in dogs with severe primary IMT.
Rozanski
Elizabeth A
EA
Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia 19104-6010, USA.
Callan
Mary Beth
MB
Hughes
Dez
D
Sanders
Nancy
N
Giger
Urs
U
D000818:Animals; D001792:Blood Platelets / Q000187:drug effects*; D004283:Dog Diseases / Q000188:drug therapy*; D004285:Dogs; D004359:Drug Therapy, Combination; D005260:Female; D005938:Glucocorticoids / Q000494:pharmacology / Q000627:therapeutic use*; D008297:Male; D010976:Platelet Count / Q000662:veterinary; D011241:Prednisone / Q000494:pharmacology / Q000627:therapeutic use*; D011446:Prospective Studies; D013921:Thrombocytopenia / Q000188:drug therapy / Q000276:immunology / Q000662:veterinary*; D016896:Treatment Outcome; D014750:Vincristine / Q000009:adverse effects / Q000627:therapeutic use*
D005938:Glucocorticoids; D014750:Vincristine; D011241:Prednisone