Factors associated with increased PMWS severity were rearing growers indoors (OR = 23.7), requiring a higher number of veterinarian visits per year (OR = 9.6), having poorly isolated hospital pens (OR = 6.4), buying replacement boars (OR = 4.8) and seropositivity to Mycoplasma hyopneumoniae (OR = 4.29); factors associated with decreased PMWS severity were low stocking density for growers (OR = 0.07), adjusting diets at least three times between weaning and 14 weeks of age (OR = 0.12), and requiring visitors to be at least 2 days pig free (OR = 0.14).
This study provides evidence of the association between environmental and management factors and PMWS severity, and suggests that other pathogens may be important co-factors for the disease. In addition, this study highlights the potential efficacy of biosecurity measures in the reduction/prevention of within-farm PMWS severity.