A novel Filobacterium sp can cause chronic bronchitis in cats.

The novel Filobacterium sp. comprises a finite part of the normal feline lower respiratory microbiome. Under certain circumstances it can increase in absolute and relative abundance and give rise to neutrophilic and/or histiocytic bronchitis, bronchiolitis and bronchopneumonia. These findings strongly suggest that F. felis could be an underdiagnosed cause of feline bronchial disease.