Leptospirosis: Why Vaccinating Your Dog Can Protect Your Entire Family

By Dr. Lohit, Main Street Markham Animal Clinic

If you’ve ever been told “Leptospirosis is rare” or “It’s just a farm dog problem,” it’s time for an update.

Leptospirosis—commonly called “lepto”—is a serious bacterial infection that’s increasingly found in urban areas like Markham. What makes lepto unique is that it's zoonotic, meaning it can be spread from animals to people.

As a veterinarian, I strongly recommend annual vaccination against lepto not just for the health of your dog, but for the health of your whole family.

🦠 What Is Leptospirosis?

Leptospirosis is caused by spiral-shaped bacteria called Leptospira, which thrive in warm, wet environments—such as puddles, dog parks, lakes, and city sewer runoff.² Dogs typically contract it by coming into contact with infected urine from wildlife like raccoons, skunks, or rats, either directly or through contaminated water or soil.

Once infected, dogs may show symptoms like vomiting, fever, lethargy, and even kidney or liver failure. But here’s the most concerning part: some dogs show no signs at all, yet still shed the bacteria in their urine, creating a silent risk for other animals and people.³

🧬 Why It Matters for Human Health

Leptospirosis is a reportable human disease in Ontario and has been on the rise.⁴ People can contract it through open wounds, mucous membranes, or accidentally ingesting contaminated water—even just touching infected urine while cleaning up after your dog could lead to exposure.⁵

In humans, lepto can cause flu-like symptoms that may progress to kidney damage, liver failure, meningitis, or even death if untreated.⁶ Children are especially vulnerable because they are more likely to play outdoors, in puddles, or with infected pets.

Urban outbreaks have been recorded in Toronto, Hamilton, and Ottawa in recent years—often in vaccinated neighborhoods where pets were not routinely protected.⁷

💉 Vaccination Is Safe, Effective, and Community-Minded

The leptospirosis vaccine is an annual injection recommended for nearly all dogs in Ontario—especially those who:

• Walk in parks or near standing water

• Visit cottages or trails

• Are exposed to wildlife (even in backyards)

• Live in areas with known cases

This vaccine is not part of the core puppy series unless requested, which means many dogs are unknowingly unprotected.⁸

By vaccinating your dog, you’re not just shielding them from kidney failure—you’re helping stop the zoonotic transmission of a disease that can harm children, elderly family members, and immunocompromised individuals.

✅ What You Can Do

• Ask your vet if your dog is up-to-date on their leptospirosis vaccine

• Avoid letting your dog drink from puddles or standing water

• Wash your hands after cleaning up pet messes or handling potentially contaminated materials

• Educate friends and family: protecting pets protects people

🗓 Book Today to Stay Protected

We’re currently seeing more cases of leptospirosis in our region, and prevention is key. Let’s work together to keep both pets and people safe.

📞 Call 905-471-1536 or book online at mainstvets.ca/bookonline to schedule your pet’s lepto vaccine or wellness exam.