Retrospective Comparison of the Efficacy of Fluconazole or Itraconazole for the Treatment of Systemic Blastomycosis in Dogs

Abstract

Itraconazole is recommended for treatment of blastomycosis in dogs. Some evidence suggests that fluconazole might be less hepatotoxic than itraconazole. 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. One hundred and forty-four dogs with systemic blastomycosis treated with itraconazole or fluconazole from 1998 to 2008. Retrospective case review. Information obtained included signalment, body weight, clinical signs, drug regimen, treatment duration, time to clinical remission, and laboratory 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). 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.