Vertical transmission of tick-borne and hemotropic pathogens in pregnant dogs: first report involving Babesia vogeli and Candidatus Mycoplasma haematoparvum

• First molecular evidence of vertical transmission of Babesia vogeli. • First molecular evidence of vertical transmission of Candidatus Mycoplasma haematoparvum. • Molecular findings support vertical transmission of Anaplasma platys . • Among hemoplasmas Candidatus Mycoplasma haematoparvum was most common in pregnant dogs • Vertical transmission may pose a challenge to vector-borne disease control. This study aimed to investigate the vertical transmission of Babesia vogeli, Hepatozoon canis, Anaplasma platys, Anaplasma phagocytophilum , and hemotropic Mycoplasma via molecular detection in 51 blood samples from naturally infected female dogs, 51 placentas, 22 organ pools from stillborn puppies, and 44 blood samples from neonates up to five days of age. As a result, vertical transmission was confirmed for A. platys in seven (31.81%) stillborn organ pool samples, and for hemoplasmas in one (14.28%) organ pool and 12 (63.15%) neonate samples. Furthermore, this study provides the first record of this transmission route for the protozoan B. vogeli in three (13.63%) stillborns and two (25%) neonates and for the hemoplasma Candidatus Mycoplasma haematoparvum in one (14.28%) stillborn and 12 (63.15%) neonates. The data contribute to a better elucidation of the epidemiology of these agents in pregnant female dogs and emphasize the need for more in-depth investigations to clarify the detailed mechanisms surrounding the vertical transmission of hemopathogens, considering that this transmission route may play an important role in the maintenance and dissemination of these agents, especially in the absence of vectors.