Three 6-week-old pigs were submitted alive for necropsy to the Animal Disease Diagnostic Laboratory at Purdue University. The pigs were from a farm that operated a multisite production system, with a farrowing site and a wean-to-finish site. Among the 4,400 pigs at the wean-to-finish site, there was an outbreak of illness with estimated morbidity rate of 20% and estimated mortality rate of 8%. Pigs at the wean-to-finish site had been born within 2.5 weeks of each other and had been weaned at 3 weeks of age. The 3 pigs submitted (all 6 weeks old) for euthanasia and necropsy were