Successful Treatment of Sino-Orbital Aspergillus udagawae Infection Using Oral Posaconazole in a Cat

A 10 yr old spayed female ragdoll cat presented with sudden onset of sneezing, nasal discharge, and stertor. There was no improvement in clinical signs despite treatment with antibiotics, feline interferon, and nebulization. A computed tomography (CT) scan revealed findings consistent with chronic rhinitis, and a tissue biopsy obtained by rhinoscopy led to a histopathologic diagnosis of sinonasal aspergillosis. Polymerase chain reaction amplification identified the causative agent as Aspergillus udagawae. Oral itraconazole therapy was initiated. However, the cat's clinical signs progressed to include left exophthalmos, nictitating membrane protrusion, and lacrimation. A second CT scan revealed a soft-tissue attenuating structure extending into the left retrobulbar space, confirming progression to sino-orbital aspergillosis (SOA). The oral medication was changed to posaconazole and continued for 5 mo, resulting in resolution of the clinical signs. The cat has remained asymptomatic over 24 mo since initial diagnosis. This case represents the first successful treatment of feline SOA caused by A udagawae infection with posaconazole. A udagawae is the second most common cause of SOA and is known to be intractable because of its low susceptibility to antifungal agents and poor response to topical clotrimazole. Posaconazole may be a valuable treatment option for SOA caused by A udagawae.