Leptospirosis is a disease that can affect many species, including humans, dogs, livestock and horses. “Lepto” is caused by spiral-shaped bacteria called spirochetes. These pathogens are often found in wildlife populations, including rats and mice. The leptospires can survive in surface water, stagnant ponds, streams, or moist soil for long periods at mild temperatures. They are short-lived in cold or hot, dry weather.