Introduction Ticks transmit a great variety of pathogenic microorganisms to humans and animals. The detection of tick-borne pathogens (TBP) is mainly by molecular techniques based on polymerase chain reactions (PCR). To design and evaluate a multiplex PCR for the molecular screening of zoonotic TBP for exploratory studies. Material and Methods Control DNA from reference strains, DNA from experimentally-infected biological specimens, and from Rhipicephalus sanguineus ticks collected from domestic and homeless dogs were used. A multiplex PCR assay to detect the presence of Borrelia burgdorferi sensu lato, Anaplasma spp. and Babesia spp. was designed and optimized using primers previously reported for B. burgdorferi sensu lato and Anaplasma spp., while for Babesia spp. they were designed in silico. The multiplex PCR was evaluated on the DNA from biological samples. Results A new set of specific primers for Babesia spp. was designed. Adjustment of the master mix reactive concentrations and amplification conditions for the multiplex PCR allowed the successful amplification of the specific amplicons for each microbial group from the control DNA and experimentally-infected biological specimens. The efficiency of the multiplex PCR amplifying three DNA targets was confirmed. Individual and co-infection of Anaplasma spp. and Babesia spp. were detected in the R. sanguineus ticks from dogs. Conclusions A multiplex PCR assay for the screening of three TBP is available. By using it, B. burgdorferi sensu lato, Anaplasma spp. and Babesia spp. can be detected accurately in one PCR reaction.