Prevalence of tick-borne pathogens in pet dogs in Lithuania

Abstract

Tick-borne pathogens (TBPs) represent a growing veterinary and public health challenge in the Baltic region, where climatic conditions support abundant populations of Ixodes ricinus and Dermacentor reticulatus ticks [1]. As the most common companion animals in Lithuania, dogs are frequently exposed to tick habitats, increasing the risk of infections with Anaplasma phagocytophilum and Babesia canis [2, 3]. Both pathogens are clinically relevant due to nonspecific clinical signs, which complicate diagnosis in veterinary practice. This study aimed to investigate the prevalence of A. phagocytophilum and B. canis in Lithuanian dogs and to characterise their genetic diversity through cytological, serological, and molecular analysis. A total of 203 blood samples from pet and hunting dogs were analysed. A. phagocytophilum prevalence reached 25% in pet dogs and 4.4% in hunting dogs. Serology and PCR results did not always coincide, underscoring the importance of molecular testing, while B. canis DNA was detected in 66.3% (62/107) of pet dogs. Importantly, discrepancies were observed between microscopy and PCR: out of 75 dogs diagnosed microscopically, only 54 were PCR-positive, while eight PCR-positive dogs were smear-negative. Four sequence variants of B. canis were identified, with Lithuanian isolates clustering with strains from Latvia, Germany, and France. Sequencing revealed multiple A. phagocytophilum genotypes, with Lithuanian isolates clustering alongside strains from Hungary, Spain, Germany, Sweden, Slovenia, and local Ixodes ricinus ticks. B. canis isolates grouped closely with strains from Latvia, Germany, and France. No significant associations were found between pathogen prevalence and host factors such as sex, age, or breed. This study demonstrates that Lithuanian dogs serve as important hosts for both A. phagocytophilum and B. canis. The molecular and phylogenetic findings confirm genetic links between local and European isolates, emphasising the need for regular screening, tick prevention strategies, and molecular surveillance to mitigate the veterinary and zoonotic risks of TBPs.