Disseminated fungal infections cause morbidity and mortality in dogs. The prognosis varies depending on the infecting agent. Phialosimplex caninus is a recently recognized type of hyalohyphomyces. Knowledge regarding the clinical course of P caninus infection in dogs is limited to two previous case reports. The clinical features, diagnostic findings, responses to medical therapy, and long-term outcomes of three dogs with disseminated P caninus are presented in this study. All dogs had improved quality of life once itraconazole administration, with or without terbinafine, was instituted. Long-term disease remission was maintained even after discontinuation of antifungal therapy in a single dog.