Photomicrographs from a Northern Shoveler (Spatula clypeata) from Utah, USA

Photomicrographs from a Northern Shoveler (Spatula clypeata) from Utah, USA. H&E stain. (A) The air sac epithelium is replaced by or covered with a thick layer of fibrin admixed with heterophils and fewer macrophages and eosinophilic and cellular necrotic debris (*). The connective tissue wall is expanded by edema and moderate numbers of heterophils (arrow). Inset: Air sac showing numerous gram negative bacterial rods. Brown and Hopps Gram stain. (B) Higher magnification of the air sac wall showing heterophils (arrowheads). (C) The epicardium is expanded by a thick layer of fibrin admixed with moderate to large numbers of heterophils and macrophages and eosinophilic and cellular necrotic debris (*). The subjacent myocardium (m) is not affected. (D) Higher magnification of the epicardium showing fibrin (arrowhead), heterophils and macrophages (arrow), and necrotic debris (*). (E) Fibrin deposits are occasionally present in hepatic sinusoids (arrow). Hepatocytes and Kupffer cells often contain intracytoplasmic brown pigment (hemosiderin; arrowhead). (F) Fibrin deposits (arrow) are observed throughout the spleen.