Polyarthritis is a common problem in preweaned pigs and affects ~18% of litters and 3.3% of pigs after 4 days of age. • Most affected pigs will die by 3 weeks of age. • Lower incidence in female pigs and pigs from multiparous sows. • Affected pigs had more cases of gingivitis than normal pigs. • Instruments should be disinfected between piglets, and the tail and navel sprayed with a disinfectants. • Streptococci cause 65% of the cases, followed by staphylococci and E. coli.