Posaconazole treatment of refractory coccidioidomycosis in dogs

Background: The majority of dogs with coccidioidomycosis recover with administration of fluconazole or itraconazole, although some cases are refractory or the dogs do not tolerate administration of these medications. Objectives: The objective was to describe the treatment outcomes and therapeutic monitoring of 8 dogs with refractory coccidioidomycosis treated with posaconazole. Animals: Eight dogs with refractory coccidioidomycosis. Methods: Retrospective case series. Medical records from Veterinary Specialty Center of Tucson were searched to identify dogs with refractory coccidioidomycosis that were treated with posaconazole. Clinical information and the results of monitoring trough serum posaconazole concentrations were retrieved. Results: Eight dogs with refractory coccidioidomycosis were treated with 2.5 to 10 mg/kg per day of posaconazole. Six of 8 dogs recovered or developed clinical remission while administered posaconazole. Thirteen serum concentrations from 8 dogs tested were >1 μg/mL (range, 1.52 to >6 μg/mL) and the drug was well-tolerated by 7 dogs. One dog required dosage reductions and treatment was ultimately discontinued because of hepatotoxicosis. Conclusions and Clinical Importance: Posaconazole should be considered as a treatment option for dogs with refractory coccidioidomycosis. Monitoring of indicators of liver function or injury along with therapeutic drug monitoring is recommended to tailor dosage in the event of hepatic toxicosis.