Tick-borne pathogens in dogs and their ticks in France: Molecular and serological evidence from a multicenter participatory study.

Canine tick-borne diseases (TBDs) are expanding globally, representing an increasing concern for both veterinary and public health. Dogs, due to their close contact with humans and frequent exposure to ticks, may serve as valuable sentinels for zoonotic risk. Between December 2022 and December 2023, we conducted a year-long multicenter participatory pilot survey in France involving veterinary clinics, dog owners, and research laboratories. Ticks and blood samples were collected from 82 dogs presented in 41 veterinary practices across 34 departments. Tick species were identified morphologically, and genomic DNA extracted from ticks and canine blood and/or serum samples was screened for selected tick-borne pathogens (TBPs) using PCR and sequencing. Serological analyses were also performed. A total of 165 ticks were collected from enrolled dogs, including Dermacentor reticulatus (29.7%), Ixodes ricinus (18.2%), Rhipicephalus sanguineus s.l. (16.4%), I. hexagonus (6.7%), and D. marginatus (0.6%). Tick submissions were recorded throughout the study period, with temporal variations observed among tick genera. Molecular screening identified several TBPs in dogs, including Borrelia garinii (n = 5) and Babesia canis canis (n = 5). Serological analyses revealed antibodies against Ehrlichia spp. and Anaplasma spp. in one and three dogs, respectively. Several infected dogs were asymptomatic. In ticks, the main TBPs detected included B. garinii, B. canis canis, Rickettsia massiliae, and R. raoultii, as well as several endosymbionts. This multicenter participatory pilot study supports the feasibility of a One Health surveillance approach based on veterinary networks for monitoring tick species and TBPs. Although the study was not designed to assess national prevalence or validate dogs as sentinels through comparison with human surveillance data, the findings provide proof-of-concept for the potential value of integrating veterinary and public health surveillance systems to improve our understanding of TBP circulation in France.