Leptospirosis is a zoonotic disease, meaning it is a disease that can be transmitted from infected animals to humans. It is a bacteria carried by wildlife; most common being deer, skunks, possums, small rodents and squirrels. It is shed through the urine of infected wildlife, therefore dogs do not need to come into direct contact with them. The bacteria are found in contaminated bodies of water and can also be picked up by walking through infected urine soaked grass.
Leptospira bacteria enter the dog/human through the mucous membranes or through an open wound and primarily attacks the kidneys and/or liver. The most common symptoms are lack of appetite, lethargy, excessive drinking & urination, vomiting. Hospitalization is recommended for the patient, with intravenous fluids and antibiotic therapy to help with the kidney/liver damage. Caring for a leptospirosis-infected dog must be done with caution to reduce the risk of transmission to humans and unvaccinated dogs. Gloves must be worn, and protective clothing to avoid contact with any urine the patient has passed.
The best way to protect your dog from getting leptospirosis is vaccinating against it. Although this is not considered a "core" vaccine, it is highly recommended for pet owners who live where wildlife is present. Even toy breeds that "only go outside to potty" are at risk of being exposed. When your dog initially receives the vaccine, it will need to be boosted in 2-3 weeks, then once yearly to maintain immunity.