Canine leptospirosis is a bacterial disease that affects dogs’ kidneys and liver and can cause serious illness or death. The disease is caused by Leptospira, a genus of spirochete bacteria composed of many genetically and antigenically distinct types, known as serovars. 

Current canine Leptospira vaccines, which are killed (bacterin) formulations covering a limited number of serovars, are effective at reducing clinical disease but have important limitations. Protection is largely restricted to the serovars included in the vaccine, immunity is relatively short-lived, and vaccination does not consistently prevent renal colonization or urinary shedding across strains. 

Given the broad diversity of Leptospira and its variability across regions and animal reservoirs, there is a clear need for broader, cross-protective vaccines. New approaches targeting conserved antigens could enhance population-level protection, reduce zoonotic risk, and limit environmental transmission.