Leptospirosis is a bacterial infection caused by Leptospira that can affect a dog’s blood, liver, and kidneys. The bacteria that cause the illness are carried primarily by brown rats and other rodents, but dogs that are infected with the disease can infect other dogs and humans as well. Ingestion of the urine of an infected animal is the most common means of transmission, but the bacteria can be contracted through damaged/thin skin and through the soft lining of the nose, mouth and eyelids.

After an animal is infected, the bacteria multiply in the bloodstream and then move into the tissues, concentrating in the liver and kidney. The dog’s immune system starts to produce an antibody response that can quickly clear most of the Leptospira bacteria from the body, but the bacteria may persist in the kidneys and be shed for weeks or months in the urine.


Leptospirosis is an odd disease that can often show no signs or symptoms at all. In these cases, the bacteria are eventually defeated by the dog’s natural defences. Other times, and more often, however, it can develop into a more severe and life-threatening illness that affects kidneys, liver, brain, lungs and heart.

If the disease is caught early enough, treatment with antibiotics is generally successful, however, often dogs that survive renal leptospirosis will have chronic kidney disease for the rest of their lives.


Vaccination and clean, hygienic conditions are the best way to avoid leptospirosis in dogs. If the animal is not able to come into contact with disease-carrying rats and their urine, the dog is unlikely to become infected, even if unvaccinated. If you are unsure whether your dog needs to be vaccinated against leptospirosis then have a chat with your vet. In areas where leptospirosis vaccinations are recommended, puppies are vaccinated at 8 and 12 weeks and then a booster every year afterwards.

• fever
• lethargy
• weight loss
• anorexia
• depression
• acute renal failure
• jaundice
• abdominal discomfort
• vomiting and diarrhea
• respiratory distress
• blood in urine is uncommon, but may occur

Dog being treated for Leptospirosis