Leptospirosis is a very contagious bacterial disease that can affect both animals and humans.  Leptospirosis, or lepto, is mostly spread by a human or an animal drinking water that has been contaminated with the urine from another infected animal. For example, if your dog likes to drink out of the little stream in your backyard, he is running a risk of becoming infected with leptospirosis. Other ways of getting lepto (althought not as common) are through breeding, gestations, membranes of eyes, ingestion of contaminated flesh, or through bites or abrasions. Lepto is more common in the spring and fall when the soil is moist, which is the perfect breeding grounds for lepto. Symptoms of the disease may include, fever, depression, vomiting, loss of appetite, or just all over pain. If left untreated, lepto can result in chronic liver and kidney disease or fatality. If your pet runs a risk for leptospirosis, he should be vaccinated every year along with his core vaccines.