Kloster et al.
Antibodies against tick-borne pathogens in domestic dogs in Norway: Borrelia burgdorferi sensu lato, tick-borne encephalitis virus, and Anaplasma phagocytophilum. Acta Vet Scand. Published online March 15, 2026. doi:10.1186/s13028-026-00863-8
In Norway, Ixodes ricinus is the most abundant tick species. It is predominantly distributed along coastal regions and has expanded its range over the past two decades. Among the most well-known tick-borne pathogens affecting canines in northern Europe are Borrelia burgdorferi sensu lato, Anaplasma phagocytophilum, and tick-borne encephalitis (TBE) virus.
Because dogs often accompany their owners during outdoor activities, their exposure to ticks may mirror that of humans, making them particularly useful for assessing human exposure risk. Monitoring canine exposure can therefore provide valuable epidemiological data relevant to both veterinary and public health.
A study conducted between 2016 and 2023 estimated the seroprevalence of IgG antibodies against the three aforementioned pathogens in domestic dogs in Norway. Blood samples were collected from 433 dogs across 15 counties, representing all five regions of the country: Eastern, Southern, Western, Central, and northern norway. The sample included a diverse population, with 106 distinct breeds represented.
Overall, 38% (165/433) of the dogs were seropositive for IgG antibodies against one or more tick-borne pathogens. Regional seroprevalence ranged from 22% in northern norway to 52% in Southern Norway. Among seropositive dogs, 72% showed evidence of exposure to a single pathogen, 22% to two pathogens, and 4% to three pathogens. Specifically, 20% tested positive for B. burgdorferi, 11% for A. phagocytophilum, and 19% for TBE virus.
The highest TBE virus seroprevalence was observed in Southern Norway (28%), followed by Central (24%) and Eastern Norway (20%). Lower prevalence rates were reported in Northern (11%) and Western Norway (11%). These findings align with the increasing number of reported human TBE cases in Norway over the past two decades (see TBE Book, Chapter 13).
The findings of this study indicate that dogs are at risk of acquiring tick-borne viral infections in Norway, and TBE should be considered among differential diagnoses in dogs presenting with neurological symptoms. Furthermore, dogs can serve as valuable sentinels for monitoring vector distribution and pathogen circulation.