Granulomatous inflammation of salt glands in ducklings (Anas platyrhynchos) associated with intralesional Gram-negative bacteria

The ‘‘nasal glands’’ occur in many bird species and are powerful sodium ion-excretory organs. In ducks, they are located in supraorbital bony recesses. Granulomatous inflammation of these glands occurs with an incidence of approximately 1% in ducklings (Anas platyrhynchos), and is not associated with specific clinical symptoms. We investigated nine glands of eight animals with granulomas by gross pathology and histopathology, and compared results of bacteriology with 20 non-lesioned nasal glands. Adenitis was characterized by multifocal to coalescent heterophilic granulomas with central necrotic heterophils, and multinucleate giant cells, lymphocytes and plasma cells. Within the centres of the granulomas, there were clusters of Gram-negative bacteria that were identified as halotolerant Pseudomonas aeruginosa, Proteus mirabilis and Aeromonas hydrophila. Normal glands contained exclusively various halotolerant Gram- positive bacteria, mostly Streptococcus sp. and Enterococcus sp. The distribution of lesions and lack of clinical symptoms were suggestive of a localized ascending infection via the secretory ductules.