Treatment of blastomycosis with itraconazole in 112 dogs

Alfred M. Legendre
Barton W. Rohrbach Dr., University of Tennessee - Knoxville
Robert L. Toal
M G. Rinaldi
L L. Grace
J B. Jones

Abstract

70 dogs with blastomycosis received 10 mg/kg of body weight of itraconazole, daily (group 1), and a second group of 42 dogs received 5 mg/kg of itraconazole, daily (group 2). The proportion of dogs cured with a 60-day course of itraconazole was similar for both groups (53.6% in group 1 vs. 54.3% in group 2) and for a control group treated with amphotericin B (57%); the recurrence rate was also similar, 20%, 21.4%, and 20%, respectively. Dogs treated with itraconazole had similar mortality rates (25.7% at 5 mg/kg; 25% at 10 mg/kg) to those treated with amphotericin B (23%). 27 of the 23 dogs that died (74%), did so during the first week of treatment; these early deaths were usually attributed to respiratory failure. The only site of infection that was significantly associated with failure (death or recurrence) was the brain. There was a marked difference in survival times between dogs without lung disease or with mild lung disease compared with dogs with moderate or severe lung disease. Serum itraconazole concentrations reached steady state by 14 days of treatment. Dogs in group 2 had mean serum concentrations of 3.552.81 mg/ml (range, 0.67 to 10.8 g/ml), whereas dogs in group 1 had mean concentrations of 13.468.49 g/ml (range, 1.8 to 28 g/ml). There was no association between cure and serum itraconazole concentrations. Dogs in group 1 had significantly more adverse effects than dogs in group 2. Anorexia was the commonest adverse effect, occurring in 14.9% of dogs in group 1. Only 8% of dogs in group 2 had adverse effects. Serum concentrations of itraconazole were positively correlated with serum alkaline phosphatase and alanine aminotransferase activities. It is concluded that itraconazole administered at a dose of 5 mg/kg daily is the drug of choice for blastomycosis in dogs.