Efficacy ofBorrelia burgdorferivaccine in dogs in North America: A systematic review and meta-analysis

Background Lyme borreliosis, a tick-borne disease, is endemic to some parts of North America and is an emerging disease in other parts of the world. Vaccination is an increasingly common, although controversial, method used in the prevention of Lyme disease in dogs; the reported efficacies of Borrelia burgdorferi vaccines in dogs are highly variable, ranging from 50% to 100%. Objectives To determine the efficacy of vaccines for prevention of Lyme disease in dogs in North America. Methods Experimental and observational study designs were eligible for inclusion. The outcome of interest was the reduction of incidence of clinical illness after exposure to B. burgdorferi. Electronic databases searched were MEDLINE, Web of Science, and Centre for Agricultural Biosciences Abstracts. Clinical signs were extracted as dichotomous outcomes: lameness, anorexia, pyrexia, depression, and lymphadenopathy. Study quality was assessed using tools from the Cochrane collaboration. Results In total, 3 observational studies and 13 challenge trials were included. None of the challenge trials assessed lymphadenopathy, but for each of the remaining 4 clinical signs, a meta-analysis was performed. Compared to unvaccinated dogs, vaccinated dogs had a reduced odds of developing lameness, depression, pyrexia, and anorexia (odds ratio: 0.15-0.23). Conclusions and clinical importance Based on the quantitative synthesis of results from challenge studies, vaccinated dogs are less likely to develop clinical signs after exposure to B. burgdorferi compared to unvaccinated dogs. These results should be interpreted with caution, however, as several shortcomings related to quality and study design were identified. Future studies should focus on larger sample sizes in field conditions.