Tracheal Collapse in a Pekin Duck ( Anas platyrhynchos domestica).

A 5-year-old, 3.72-kg female Pekin duck ( Anas platyrhynchos domestica) was presented for acute respiratory distress, head shaking, and collapse. Similar spontaneously resolving episodes had previously occurred. Physical examination revealed severe inspiratory and expiratory dyspnea. Due to poor prognosis, euthanasia was elected. Postmortem examination revealed severe tracheal collapse involving the proximal trachea. The tracheal lumen was reduced in size by 75%. Histologic evaluation revealed ossification of the tracheal rings for approximately 60%-100% of their circumference. The bone trabecules presented characteristics of mature bone with a medullar cavity containing hematopoietic cells and adipocytes. There was also osseous metaplasia of the cartilage. In the lamina propria, there was lymphocytic infiltration and fibrosis, both moderate. To our knowledge, tracheal collapse has not been reported in a Pekin Duck.