Leptospirosis is a bacterial disease of dogs with zoonotic risk that is increasing in urban and suburban environments, making current vaccination essential welfare protection.
Leptospirosis creates acute, severe welfare impact: the disease progresses rapidly from apparent normality to life-threatening organ failure, with affected dogs deteriorating visibly within hours. Successful treatment requires intensive hospitalization care that is both expensive and itself welfare-challenging - hospitalized, seriously ill dogs experience isolation, repeated procedures, and systemic illness simultaneously. The re-emergence of leptospirosis in urban dog populations has been linked to increasing rat populations and dog exposure to waterways during outdoor recreation. Dogs presented early in disease course with supportive care have better outcomes than those presenting in advanced organ failure. Vaccination with L4 vaccines covering four serovars provides effective protection but requires annual boosting due to short immunity duration. The zoonotic risk adds a public health dimension to the welfare argument for vaccination, creating dual motivation for vaccination compliance.