Culture-independent and dependent evaluation of the equine paranasal sinus microbiota in health and disease.

The microbiota of the paranasal sinuses of horses consists primarily of aerobic bacteria and fungal organisms, the majority of which are uncultivable via common clinical methods. Anaerobic bacteria are found in the majority of horses with clinical sinusitis. These findings suggest anaerobic bacteria are associated with sinusitis and their presence should be considered when treating horses with sinusitis.