Here is information from the cdc about lepto....it is good to know exactly what it is and whether or not your pup is at risk. I do not believe there is any blanket statement that all pups should not get this vaccine. Also good to speak with your vet about WHY he feels that any vaccine is necessary and then do your homework from trusted sources and go back and speak with your vet before letting him/her vaccinate your pup.
Disease Listing, Leptospirosis and Your Pet | CDC Bacterial, Mycotic Diseases