Kaplan-Maier survival rate curves. Piglets were vaccinated with the equivalent to 109 CFU/mL of S. suis strain P1/7 bacterin formulated either with Alhydrogel® (A), Emulsigen®-D (B), Quil-A® (C), Montanide™ ISA 206 VG (D), Montanide™ ISA 61 VG (E), or Montanide™ ISA 201 VG (F). All piglets were challenged intraperitoneally with 5 × 109 CFU of S. suis strain P1/7. Each vaccine formulation group of vaccinated piglets (n = 10) had a corresponding placebo group of piglets (n = 10) challenged at the same time. The clinical signs observations were conducted three times per day, nine days post-infection. *, P < 0.05.