Leptospirosis is a serious infection of people and pets. As with much of preventive care the recommendations vary with lifestyle and location. Lepto does tend to be more of a problem in urban areas due to a higher density of rodents which serve as a host and spread the organism to other mammals. We recommend lepto vaccination but we do not give it until at least nine weeks and often not until 12 weeks which seems to reduce the incidence of side effects. Your veterinarian can guide you based on the area you live.