If your dog engages in unsafe practices such as eating feces, or as my one dog does - rolling in mud holes where a raccoon may have made a boo-boo in the middle of the night, then one should vaccinate. If your dog is not in a position to come into contact with contaminated water or feces, then it's a non-issue. When in doubt vaccinate.

Lepto is a very nasty disease for a dog to get, and as one poster has stated can kill. There are no studies out that links lepto vaccinations to a vaccine side effect. Most likely because they are usually given at the same time as other vaccines, and the Lepto vaccine can not be parsed out as the cause.

Puppies are usually given a 3 week booster, whereas adult dogs are not. The efficacy of the Lepto vaccine is not a shot in the dark per the US. The two most common strains in the US pomona and grippotyphosa are covered in the vaccine, and provide some protection against other common US serotypes. On the other hand France and especially Germany seem to have serotypes not covered by the vaccine. Surprise - where did the vaccines most likely originated from (per original regulatory applications) ... the US.