As the summer heat fades away and the beautiful colours of fall take over, there is the lurking threat of an emerging disease that can be life threatening for our dogs. Leptospirosis is a bacterial infection that is transmitted by wildlife (raccoons, skunks, rodents) via their urine, through bite wounds or by eating infected tissue. The bacteria is typically found in stagnant or slow moving water and can remain in the environment for months in optimal conditions with summer and late fall showing the highest occurrence – this could be seen as much in High Park as it can in your backyard. A Connecticut study has shown that 48% of raccoons, 13% of skunks and nearly 50% of rodents showed positive Leptospirosis levels. Furthermore, a recent Michigan study showed 25% of ‘healthy’ dogs had tested positive for Leptospirosis. Interestingly, there is no breed preference – for example, German Shepherds as well as Yorkshire Terriers showed very similar likelihood.


Dogs that have been exposed to the bacteria typically show signs such as: vomiting, diarrhea, decreased appetite, stiffness, fever and lethargy. These signs can potentially lead to kidney failure, liver disease, lung disease, meningitis and immune mediated disease. Due to the fact that Leptospirosis is zoonotic (can be passed from animals to people) as well as the fact that the animal affected can be a reservoir (do not necessarily show symptoms but can shed bacteria furthermore), it is imperative to establish a diagnosis as quickly as possible. This can be achieved by way of blood and urine tests as well as the possibility of imaging (x-rays, ultrasound).


Those that are showing symptoms as well as laboratory evidence of Leptospirosis are often hospitalized. Antibiotics are the key to treating Leptospirosis and reducing the spread of the disease to other animals but importantly, to people as well. Prognosis depends on the manifestation of infection, severity and the general health status of the dog. With early diagnosis and swift treatment, survival rates are approximately 80%; however with delay, mortality rates have been shown to range from 11 to 48%!


Vaccination is a very effective means to reduce the occurrence as well as the severity of disease. We at Dundas West Animal Hospital have recently made Leptospirosis a ‘core’ vaccine (every dog should receive this vaccine) as there is growing evidence that this is an emerging disease that will continue to worsen with the continuation of urban sprawl. Further prevention can be achieved by decreasing access to standing water and minimizing exposure to wildlife. Please contact your local veterinarian should you have any questions.


Dr. Alex Folosea

Co-owner, Dundas West Animal Hospital