Retrospective comparison of the efficacy of fluconazole or itraconazole for the treatment of systemic blastomycosis in dogs.

Background: Itraconazole is recommended for treatment of blastomycosis in dogs. Some evidence suggests that fluconazole might be less hepatotoxic than itraconazole.
Objectives: To compare (1) incidence of clinical remission and death; (2) treatment duration; (3) total drug cost; (4) incidence of relapse; and (5) incidence of increased ALT activities in dogs with blastomycosis treated with fluconazole or itraconazole.
Animals: One hundred and forty-four dogs with systemic blastomycosis treated with itraconazole or fluconazole from 1998 to 2008.
Methods: Retrospective case review. Information obtained included signalment, body weight, clinical signs, drug regimen, treatment duration, time to clinical remission, and laboratory results.
Results: Neither treatment efficacy between fluconazole (75% remission) and itraconazole (90% remission) nor relapse rate (18% for itraconazole, 22% for fluconazole) was significantly different (P = .13, .75, respectively). Treatment duration was significantly longer for fluconazole (median 183 days) than for itraconazole (138 days; P = .001). Costs for fluconazole (median $1,223) were significantly less than for itraconazole ($3,717; P < .001). Incidence of increased ALT activities was not significantly different between groups (17% [3/18] for fluconazole, 26% [6/23] for itraconazole; P = .71).
Conclusions: Fluconazole is associated with survival to clinical remission in 75% of dogs with blastomycosis. Although dogs receiving fluconazole were treated longer, drug costs were one-third those of itraconazole. Hepatotoxicosis, as estimated by increases in serum ALT activity, can be observed with similar incidence for both drugs.
(Copyright © 2011 by the American College of Veterinary Internal Medicine.)