Back to Care


Leptospirosis is a disease caused by spiral shaped bacteria called leptospires. Humans and animals become infected through contact with contaminated urine, water or soil. The bacteria enter the body through skin or mucous membranes, such as the eyes, nose or mouth, especially if the skin is broken from a cut or scratch.

Even pets living in suburban areas are often exposed to wildlife, such as raccoons, skunks, squirrels, opossums or deer that are infected with leptospirosis.

Drinking contaminated water can also cause infection. Infected wild and domestic animals may shed the bacteria into the environment continuously or every once in a while for a few months up to several years. 

Dogs are generally infected by drinking, swimming or walking through contaminated water. Even pets living in suburban areas are often exposed to wildlife, such as raccoons, skunks, squirrels, opossums or deer that are infected with leptospirosis. Dogs may also pass the disease to each other; however, this happens rarely. All animals can potentially become infected with leptospires, although cases in cats are rare. Leptospires prefer warm weather and are readily killed by freezing, so the incidence of disease is greatest between July and December and after periods of wet weather. 

The symptoms of leptospirosis vary and are not really specific. Some dogs do not have any symptoms. Common symptoms include fever, vomiting, abdominal pain, diarrhea, refusal to eat, severe weakness and depression, stiffness, and/or severe muscle pain.  Younger animals are generally more seriously affected than older animals. The bacteria most commonly affect the kidneys and liver. Infection may result in sudden death or become chronic and produce kidney failure, hepatitis, fever or eye infections. The time between exposure to the bacteria and development of disease is usually 5 to 14 days, but can be as short as a few days or as long as 30 days or more. 

Leptospirosis is not always easy to diagnose. Blood testing to detect antibodies can be performed; however, a second sample called a titer would take place between two and four weeks after the first sample. Tests may also be run on urine. 

Leptospirosis is treatable with antibiotics. If treated early, the dog may recover more rapidly and liver and kidney disease may be less severe. Intravenous fluids are often crucial to support blood flow through the damaged kidneys so that recovery is possible.  In a study from the University of California at Davis, dogs with mild to moderate disease received IV fluids and antibiotics and 82% survived. Dogs with moderate to severe disease tended to require hemodialysis. The prognosis was worse for severely affected dogs that did not receive hemodialysis, while 86% of those receiving hemodialysis survived. 

There are two main ways to prevent leptospirosis. One is to keep rodent problems under control, since rodents can carry and spread the bacteria. The other means of prevention is to get your dog vaccinated. The vaccine does not provide 100% protection because there are many types of leptospires and the vaccine only protects against four of the types.   Vaccination will reduce the severity of the disease but will not prevent infected dogs from becoming carriers. It is also important to have your dog vaccinated even if it gets leptospirosis because he can still get infected with a different type. The leptospirosis portion of many vaccines has been associated with vaccine reactions more often than any other portion of the vaccine. However, as technology has improved, vaccines made from leptospires grown in protein-free media have made vaccination reaction far less likely. 

If your dog has been diagnosed with leptospirosis, it is important to avoid contact with urine, blood or tissues from your pet. Your pet should take all prescribed medication and should have veterinary follow-ups as recommended. Normal daily activities with your pet will not put you at high risk for leptospirosis infection; however, if you show any symptoms such as fever, muscle aches or headaches within three weeks of exposure, you should see your physician.