Clinical presentation, case definition, and diagnostic guidelines for porcine periweaning failure to thrive syndrome

Porcine periweaning failure to thrive syndrome (PFTS) is a clinical condition characterized by anorexia, lethargy, and progressive debilitation of pigs occurring within 2 to 3 weeks after weaning. In affected populations, there is a striking contrast between the clinically affected pigs, which progress from being normally active to lethargic within days of weaning, and the unaffected members of their cohort, which grow and behave normally. The etiology, pathophysiology, and pathogenesis of PFTS have not been determined, although several infectious agents have been identified in affected pigs. Histopathologic lesions of chronic active rhinitis, superficial gastritis, atrophic enteritis, superficial colitis, and thymic atrophy are observed in most PFTS-affected pigs. The basis for a presumptive diagnosis of PFTS includes the age of onset, the presence of typical clinical signs, the presence of the collective histopathologic lesions, and, importantly, the ruling out of other known swine diseases (for example, porcine circovirus associated disease, swine influenza, porcine reproductive and respiratory syndrome, and bacterial infections). The objectives of this paper are to propose a clinical case definition, describe the characteristic clinical progression, signs, and observed lesions of PFTS, and to make recommendations for investigation of PFTS-suspected farms.