Serological test for B. burgdorferi s.l. used in this study is sensitive and specific (94% and 99.5% respectively) and detects C6 protein of B. burgdorferi s.l. that is specific to the natural infection, thus vaccinated dogs would be excluded (Beall et al., [5]; Pantchev et al., [12]; Couto et al., [16]). Here, C6 is linked to infection.