CASE DESCRIPTIONA 5-year-old 34.3-kg (75.5-lb) neutered male German Shepherd Dog was evaluated because of chronic azotemia that was unresponsive to typical medical management.CLINICAL FINDINGSUrinalysis revealed pyuria and fungal hyphae. Fungal culture of a urine sample grew a sterile mold that was identified as Westerdykella spp via PCR assay. TREATMENT AND OUTCOME-: he dog was treated empirically with itraconazole orally and amphotericin B IV for 5 weeks. Because of progressive azotemia, treatment was modified to oral administration of posaconazole. The dog improved but then developed progressive azotemia, hyperphosphatemia, and suspected diskospondylitis. Treatment was again modified to oral administration of terbinafine on the basis of results of antifungal susceptibility testing. The dog was euthanized after 5 months of antifungal treatment because of a deteriorating clinical condition and progressive azotemia.CLINICAL RELEVANCEWesterdykella spp are filamentous hyphal organisms from the family Sporomiaceae and had not previously been reported to cause infections in dogs. Fungal PCR assay and antifungal susceptibility testing may be useful for a patient with a suspected fungal infection that does not respond to empirical treatment or when traditional culture methods for fungal identification are unsuccessful. Westerdykella spp should be considered as a possible etiologic agent when systemic mycosis is diagnosed.