Clinical remission of feline sino-nasal aspergillosis despite evidence of persistent infection

CASE SUMMARY: Feline sino-nasal aspergillosis is a rare condition with only sparse heterogeneous reports in the literature regarding its treatment. This report describes the presentation, treatment and outcome of a cat with sino-nasal aspergillosis treated by meticulous debridement in combination with topical and systemic azole therapy. Diagnosis was based on MRI, in combination with rhinoscopic assessment and visualisation of fungal plaques, followed by histopathology, fungal culture and panfungal PCR. The cat was treated by debridement of fungal plaques via anterior rhinoscopy and frontal sinusotomy and local instillation of 1% clotrimazole solution, followed by a 4-week course of oral itraconazole. Histopathology confirmed fungal rhinitis and culture identified Aspergillus fumigatus and Aspergillus versicolor. Clinical remission was achieved after treatment; however, evidence of persistent infection was confirmed in the post-mortem examination 8 months after the cat was euthanased for unrelated reasons. RELEVANCE AND NOVEL INFORMATION: Despite clinical remission, the persistence of fungal infection post mortem highlights the challenges of monitoring the response to treatment and illustrates that the resolution of clinical signs does not necessarily equate with a disease cure.