Unusual histopathologic features in thymic corpuscles associated with porcine periweaning failure-to-thrive syndrome

Six, 5-6-wk-old pigs, from 3 farms of the same company, with significant loss of body condition were submitted for postmortem evaluation. Macroscopically, the main lesion observed in all of the pigs was thymic atrophy. Microscopically, all of the pigs had thymic atrophy, superficial lymphocytic fundic gastritis, atrophic enteritis, superficial colitis, and neutrophilic and lymphocytic rhinitis, leading to a diagnosis of porcine periweaning failure-to-thrive syndrome. In the pigs from 2 of the farms, many of the thymic corpuscles had infiltrates of neutrophils and degenerate cells, in some cases infiltrating the surrounding parenchyma.