Haemophilus parasuis is the cause of Glässer’s disease, and detection is difficult since pigs can be carriers with no clinical signs. A new multilocus variable number of tandem repeat analysis (MLVA) was used, and identified two genetic groups in isolates. Specific serotypes were associated with the genetics groups, but no specific virulence genes were found. Although genetic material could transfer within a group, it did not appear to do so frequently in between groups. The strain that causes Glässer’s disease was identified even though the genes were not.