What is Leptospirosis?


Leptospirosis is a bacteria spread through urine or other body fluids (not saliva) of infected wild or domesticated animals. It can be spread through water, soil or food contaminated by infected animals such as rats, possums, skunks or raccoons. As a result, dogs can become indirectly infected when the bacteria is ingested through contaminated soil and water. The bacteria can also directly infect animals or humans by penetrating skin wounds and mucous membranes.



The leptospirosis bacteria can survive for months in cool moist soil as long as it is not exposed to direct sunlight or freezes. Lepto can often be found in southern Ontario due to our seasonal changes in temperatures. Infected wild and domestic animals can shed bacteria continuously or intermittently for months to years in its carrier state. The greatest risk of infection happens when a dog is exposed to contaminated water (lakes, ponds, puddles) in areas with high numbers of wildlife, spending time near or on a farm with cattle or in areas with a  rodent infestation. Consequently, the risk of a leptospirosis infection is higher in spring and fall during the “wet” season.

Signs and Symptoms

Most cases are diagnosed between July and December in rural or suburban environments. While any age can be infected with lepto, younger animals tend to be more severely affected than older animals. Some of the affected animals may be asymptomatic while carrying the leptospirosis bacteria and others may show symptoms such as:

  • Gastrointestinal symptoms (vomiting, diarrhea, abdominal pain, anorexia)
  • Severe weakness, lethargy, and depression
  • Stiffness and muscle pain
  • Miscarriage or stillbirth in pregnant animals

Clinical signs are noted in dogs once the bacteria have spread through the kidneys and liver following 1 – 2 weeks of unexplained illness. The most common sign of this chronic phase is an increase in water consumption.

Treatment and Prevention

Treatment for Leptospirosis usually includes hospitalization for IV fluids, antibiotics, and supportive care.
If treated early most dogs recover rapidly and do not have long term health problems.

Prevention for dogs includes annual vaccination for those at greater risk of exposure. The vaccine contains 4 strains of leptospirosis, however other strains are present in wildlife and cattle.


OAHN Infographic Lepto


Leptospirosis is a zoonotic disease, meaning the bacteria can be spread from animals to people. The symptoms manifested in humans are the same as seen in dogs. Therefore, precautions need to be taken when handling a pet confirmed or suspected of carrying leptospirosis. There is a higher risk for pregnant women as lepto can cause disease in the fetus, miscarriage or stillbirth.

  • Do not handle or contact urine, blood, feces or tissues, and if necessary wear gloves and protective clothing
  • Wash hands after handling animals or anything that may have a pet’s excrement/urine on it
  • Clean potentially contaminated surfaces with an antibacterial or bleach solution

Please ask one of our veterinarians to determine the best vaccines for your dog’s lifestyle.