SPONTANEOUS STEATITIS OF EPICARDIAL FAT IN FARMED WHITE STURGEON (ACIPENSER TRANSMONTANUS)

The hearts of 235 white sturgeons originating from an intensive farm system were examined in detail. Skin, muscle and abdominal viscera did not show any pathological features, except for the presence of liver and epicardial fat. All sturgeons had high levels of epicardial fat and 70% showed important variations in colouration, which was from grey/brownish to blackish. Histopathological examination revealed lymphocyte infiltrates, around the blood vessels as small focal lesions near the intercellular spaces, or as thin strips along the borders of fat tissue. In severe cases, heavy lymphoid infiltrates and proliferative lesions were evident and fatty tissue was replaced by inflammatory and proliferative tissue. The underlying myocardium was rarely affected. A diagnosis of infiltrative and proliferative steatitis is postulated. Moreover, a high percentage of the livers showed steatosis. Aetiology is still unknown, but the authors envisage a nutritional imbalance linked with oxidised fat intake.