Mycotic Rhinitis and Sinusitis in Florida Horses

Area of Science:

• Veterinary Mycology
• Equine Pathology
• Molecular Diagnostics

Background:

• Rhinitis and sinusitis in horses can be caused by fungal pathogens.
• Subtropical and tropical regions, like Florida, may present unique etiological challenges.
• Accurate identification of fungal agents is crucial for effective treatment and disease management.

Purpose of the Study:

• To investigate and identify fungal pathogens responsible for rhinitis and sinusitis in Florida horses.
• To characterize the histomorphologic features of these equine respiratory infections.
• To evaluate the utility of molecular techniques, such as PCR and DNA sequencing, in pathogen identification.

Main Methods:

• Biopsy samples from 52 horses with respiratory signs were analyzed.
• Routine histopathology and histochemical assessments were performed.
• Polymerase chain reaction (PCR) with panfungal/panoomycete primers and DNA sequencing (DNA barcoding) were utilized on extracted DNA.

Main Results:

• Zygomycosis/pythiosis (31 cases) and phaeohyphomycosis (16 cases) were the most prevalent fungal infections.
• PCR and DNA sequencing identified fungal pathogens in 21% of cases.
• Previously unrecognized forms of equine rhinitis/sinusitis caused by fungi including *Flavodon flavus* and *Curvularia lunata* were described.

Conclusions:

• Fungal rhinitis and sinusitis are significant health issues for horses in Florida.
• Histopathology combined with molecular methods offers a comprehensive approach to diagnosing these infections.
• The study identified several novel fungal agents contributing to equine respiratory disease.