Leptospirosis Fact Sheet

Leptospirosis Fact Sheet

courtesy of Intervet

Leptospirosis is an infectious disease that causes serious illness in dogs, other animals, and people in Canada and around the world.  The disease is caused by spiral-shaped bacteria called leptospires that live in water or warm, wet soil.  Leptospirosis causes a variety of flu-like symptoms, but it can develop into a more severe, life-threatening illness that affects the kidneys, liver, brain, lungs and heart.

How do dogs become infected with leptospirosis?

The most common way dogs become infected with leptospirosis is by coming into contact with the urine of infected animals - usually in water or on wet ground.  Dogs become infected by swimming in or drinking contaminated water or by playing in areas where infected urine is present.

Leptospires enter the body through the dog's eyes, nose, or mouth, through a break in the skin caused by a cut or scratch or if the skin has been softened by prolonged exposure to water.  Once a dog has become infected, the leptospires reproduce, multiply, and begin to spread to other parts of the body.  If the infection reaches the kidneys and bladder, the dog may become a carrier of leptospirosis, spreading the bacteria each time it urinates. 

What are the signs of canine leptospirosis?

While some dogs will have no obvious symptoms, early signs of leptospirosis usually appear about a week after infection and may include fever, muscle weakness, and a loss of appetite or energy.  Some dogs may seem depressed.  Other clinical signs include jaundice (yellow eyes or skin) and blood in the urine.

Vomiting and diarrhea may follow after a few days, causing dogs to become dehydrated and very thirsty.  This is a warning sign that the infection has reached the kidneys and the dog needs immediate medical care from a veterinarian. 



Loss of appetite

Loss of energy




How serious is leptospirosis in dogs?

More than 80% of dogs with leptospirosis develop serious, short-term kidney problems.  And while most dogs do get better with prompt treatment, dogs that suffer severe liver or kidney damage can die within days..  Even dogs that do recover may still be at risk for chronic kidney failure or become carriers of the disease, spreading leptospires during urination. 

How is leptospirosis diagnosed?

Leptospirosis can be difficult to recognize by its clinical signs because the infection affects many different areas of the body and causes a variety of symptoms.  However, your veterinarian can diagnose the infection by testing your dog's blood or urine.


What can be done if my dog becomes infected?

Prompt medical treatment is critical for limiting the spread of the infection to your dog's kidneys, bladder, and liver.  The standard treatment for leptospirosis includes intravenous antibiotics and fluids, good nutrition, and supportive care.  If the treatment is started early enough, most dogs recover after 2 weeks.  Your veterinarian may then prescribe a course of oral antibiotics to make sure the infection is gone and to keep your dog from becoming a carrier of the disease. 

Be aware:

If your dog has been diagnosed with leptospirosis, you need to take measures to protect yourself and other family members, as the infection can be spread to people.  Use rubber gloves when handling your dog's urine specimen and when disinfecting the dog's bedding, housing and surrounding areas. 

Is my dog at risk for infection?

Previously thought of as a warm-weather disease, canine leptospirosis has now been reported in Ontario, Quebec, the Atlantic provinces, and British Columbia.  It occurs in rural, suburban, and city settings.  No matter where dogs live, certain factors can raise their risk of infection.  Dogs at higher risk for leptospirosis include rural dogs (working, hunting, and herding dogs), suburban dogs (dogs living near water or wildlife), and city dogs (dogs in crowded shelters or exposed to rodents). 

How can I help reduce my dog's risk of leptospirosis? 

You can try to lower your dog's risk of leptospirosis by limiting exposure to potential sources of contamination (stagnant water, rodents, unmaintained canine facilities), but the best way to reduce your dog's risk is with an annual vaccination.  Currently, vaccines are available for the 4 most common types of leptospires.

Is vaccination against leptospirosis safe?

Dogs have been vaccinated against leptospirosis for many years, and while minor side effects do occur, the vaccines are generally safe and well tolerated.  Sometimes dogs experience tenderness or swelling at the injection site that usually goes away very quickly.