Vaccination of humans and animals is a cost-effective measure for prevention of infectious diseases. The quality of newly produced batches of established human and veterinary vaccines, including inactivated Leptospira vaccines, is often tested using laboratory animals to confirm that they are safe and efficacious. Because of large numbers of animals used, the pain and distress inflicted on these animals, as well as the variability and poor reproducibility of animal tests, development of animal-free methods for batch quality control is encouraged. Standardization of vaccine manufacturing processes, adherence to Good Manufacturing Practice (GMP), and implementation of in-process testing have led to production of less variable vaccine batches. Therefore, demonstration of consistency in vaccine manufacturing has been proposed as an alternative to the current animal tests. This consistency approach relies on assessment of a set of pre-defined parameters to compare the quality of newly produced batches with that of earlier batches found to be safe and efficacious. In this thesis, we investigated whether immunostimulatory properties of canine Leptospira vaccines and individual vaccine components could be assessed in in vitro cellular assays. We have used different immune cells ex vivo as well as established cell lines to demonstrate activation of innate and adaptive immune responses in vitro. In the future, cell-based assays combined with antigen quantification may be used as part of the consistency approach in routine quality control of canine Leptospira vaccines, and hence contribute to the reduction of animal use in vaccine manufacturing.