A 2-month-old 17.0-kg (37.4-lb) black and white crossbred gilt (Sus scrofa; 1/130 pigs) was found dead on the premises of a grower-finisher operation. There were no reported signs of sickness, and no other pigs were reported dead or ill at that time. Recently, the producer had changed the operation's feed supplier.
On gross examination, the pig's pericardial sac contained approximately 20 mL of serous fluid mixed with a few strands of fibrin (Figure 1). The heart was pale brown with linear or splotchy subepicardial hemorrhages. The trachea contained white to pale pink foam