Fungal Rhinosinusitis in Cats in the United Kingdom: 34 Cases (2013–2022)

Background: Feline fungal rhinosinusitis is an uncommon condition with sparse literature regarding the presentation, causative agents, diagnosis, treatment and prognosis within the UK. Hypothesis/Objectives: To describe and report the presenting clinical signs, diagnostic imaging findings, treatment approach, and outcome of cats diagnosed with fungal rhinosinusitis in the UK. Animals: Thirty-four client-owned cats diagnosed with fungal rhinosinusitis. Methods: Retrospective multicentre observational study. Cases presenting at 10 UK referral centres between January 2013 and December 2022 were retrospectively recruited. Results: Median duration of clinical signs was 3-months (0.5-42-months). The most common signs were sneezing (79.4%) and nasal discharge (61.8%). Turbinate lysis was present in 79.4% of cases and always involved the caudal nasal cavity. Osteolysis of the frontal bone, orbit or cribriform plate was observed in 47.1% of cases. At least two tests from fungal culture, panfungal PCR, and histopathology were performed in all cases and in 23.5% of cases only one was positive. Treatment approach varied with debridement, topical clotrimazole and systemic azole therapy used alone or in various combinations, and repeat treatment occurred in 26.4% of cases. Clinical remission >90-days after treatment was found in 37.5% of cases, but mortality rates were low with 8.8% of cases dying with clinical disease during available follow-up. Conclusions and clinical importance: Fungal rhinosinusitis should be considered in cats of any age with clinical signs of nasal disease. The prognosis appears guarded for cats with fungal rhinosinusitis with <50% of cats achieving long term clinical remission.