Worldwide investigations of Giardia duodenalis have enhanced our understanding of the biology, pathogenesis, epidemiology, and complex taxonomy of this protozoan parasite, which has zoonotic potential. Modern genotyping tools, such as multilocus sequence typing (MLST), allow for the differentiation of zoonotic assemblages A and B from non-zoonotic assemblages C to H. However, many questions about the transmission cycles between infected animals and humans remain unanswered. Given the close interaction between dogs and humans, determining Giardia assemblages in dogs is crucial for assessing zoonotic risks. This study aimed to identify Giardia assemblages in household and shelter dogs across seven South Eastern European countries, analyzing 1,671 fecal samples collected from 2010 to 2014. Enzyme-linked immunosorbent assay (ELISA) detected Giardia infections in 33.7% of the dogs, with prevalence rates varying by country. Shelter dogs showed significantly higher infection rates than household dogs. Positive PCR results indicated the presence of dog-specific assemblages C and D, while zoonotic assemblages A and B were not detected. Additionally, some samples exhibited 'assemblage swapping,' where two different assemblages coexisted. Overall, G. duodenalis was found in dogs from all studied countries, but the absence of zoonotic assemblages suggests no zoonotic potential from this canine population.
