Leptospirosis is a bacterial disease spread through the urine of infected rats, wildlife, and canines. Although it is treatable with antibiotics if it is caught early, the disease can be fatal to dogs—particularly puppies and young animals. Symptoms can range from mild lethargy and depression, to more serious symptoms like abdominal pain, jaundice, and liver damage. Leptospirosis illness leads to death in approximately 20 percent of cases, usually because the early symptoms are common to many diseases and may go unrecognized.
Read more here: Leptospirosis Vaccine May Be Killing Dogs