Leptospirosis is a bacterial infection that can cause liver and kidney damage to dogs. The Lepto vaccine protects your dog against this infection.
Rodents are the most common carriers of bacteria.
The East Coast Midwest and South are more likely to contract Leptospirosis.
The vaccine would not guarantee your dogs total protection against Lepto but it will provide a high level of protection.
In the United States this bacteria isnot a threat so its not given to pets routinely - your veterinarian will advise you about how appropriate it will be for your pet.