Leptospirosis is a bacterial infection often causing permanent kidney and liver damage in dogs. It is a bacterial disease which attacks the kidneys and the liver, causing uremia (uremic poisoning), jaundice, and sometimes death. The disease is highly contagious and often fatal. It is transmitted by many species of wild and domestic animals, including rats. Both dogs and humans contract this disease through contact with infected animals or through leptospira-contaminated drinking water.
Vaccination of puppies is recommended to begin at 12 weeks-of-age and be repeated every two to four weeks until 16 weeks-of-age. An annual booster vaccination should be given for life, or as recommended by your veterinarian.
From: VIP Petcare