Phaeohyphomycotic Rhinitis Caused by Bipolaris hawaiiensis in a Horse.
Authors: Legere Rebecca M, Wooldridge Anne A, Sandey Maninder, Hanson R Reid, Cole Robert
Journal: Journal of equine veterinary science
Summary
# Editorial Summary: Phaeohyphomycotic Rhinitis Caused by *Bipolaris hawaiiensis* in a Horse A 19-year-old Quarter Horse mare presented with a four-month history of stertor and exercise intolerance, which endoscopy and CT imaging revealed to be a soft tissue mass eroding through the rostral nasal bone with generalised proximal nasal oedema. Tissue biopsy identified the lesion as a fungal granuloma caused by *Bipolaris hawaiiensis*, marking the first reported case of this organism in equids and representing an unusually aggressive form of phaeohyphomycotic rhinitis. Despite surgical debridement and antifungal therapy guided by fungal sensitivity testing, the infection progressed inexorably, ultimately necessitating euthanasia. The case underscores several significant clinical challenges: the organism's invasive nature even in an apparently immunocompetent host, the scarcity of reliable *in vivo* efficacy data for antifungal agents in horses, and the difficulty of achieving adequate drug concentrations in nasal tissues. For practitioners, this case serves as a cautionary example that fungal rhinitis should remain in the differential diagnosis for horses with chronic nasal obstruction, particularly following documented or suspected nasal trauma, and that prognosis may be guarded regardless of intervention once deep tissue invasion has occurred.
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Practical Takeaways
- •Bipolaris hawaiiensis should be considered as a differential diagnosis for horses presenting with chronic stertor, exercise intolerance, and nasal masses, particularly following potential traumatic nasal injury
- •Phaeohyphomycotic infections in horses can be highly aggressive and treatment-resistant despite surgical intervention; early diagnosis through biopsy and fungal culture is critical for treatment planning
- •Practitioners should be aware of significant limitations in antifungal drug efficacy and availability for equine fungal rhinitis, and discuss realistic prognosis and management options (including palliative care) early with clients
Key Findings
- •First reported case of Bipolaris hawaiiensis infection in an equid, presenting with aggressive clinical course and progressive disease despite surgical debridement and antifungal therapy
- •Fungal infection eroded through rostral nasal bone causing generalized proximal nasal edema and soft tissue mass formation
- •Organism demonstrated aggressive behavior in an apparently immunocompetent 19-year-old Quarter Horse mare, resulting in fatal outcome
- •Limited in vivo efficacy data for antifungal agents in equids and pharmacokinetic challenges complicated treatment decisions