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The leptospirosis vaccine for dogs protects against lepto, a bacterial infection dogs usually pick up from the urine of infected wildlife, and in southern Ontario rats and raccoons are thought to pose the biggest risk. So a city dog nosing around a Toronto park can be exposed, not just a farm dog, and it's worth asking your vet about the vaccine even if you never leave the city.
Think about your dog's usual walk. The puddle by the laneway, the ravine trail, the corner where the green bins sit. That's lepto territory.
Whether your dog needs the shot is a conversation with your vet about where you live and how your dog spends its days. This guide covers how lepto spreads, who's at risk, how the schedule works and what signs to watch for.
What is leptospirosis, and how do dogs get it?
Leptospirosis is an infection caused by Leptospira bacteria. The Merck Veterinary Manual says it often spreads by direct contact with the urine or other body fluids of an infected animal, and that urine left in the environment can spread it when conditions suit. The Toronto Humane Society adds that dogs can be infected when cut or irritated skin touches contaminated urine or water.
In southern Ontario, rats and raccoons are thought to pose the biggest risk, according to the Ontario Veterinary College's Worms & Germs Blog. The danger collects in wet places where wildlife urinates: puddles, ponds, ditches, any standing water. And it has a season. The same blog described a surge of cases in the fall.
Merck notes that any dog, of any age, breed or sex, can get leptospirosis. It isn't limited to large dogs or dogs that live mostly outdoors.
Why lepto is serious, for dogs and people
Lepto is serious because it attacks the kidneys and liver. Merck says sudden kidney injury has been the most common form of canine leptospirosis in recent years, and liver disease can come with it or on its own. The Toronto Humane Society lists fever, bruising or bleeding, and kidney and liver failure among the signs.
It's also zoonotic, meaning people can catch it. Merck says infections in people aren't common, with occupational exposure a risk factor, and the Toronto Humane Society notes people can catch it from infected dogs and rats.
Go to a vet or an emergency clinic now if your dog is lethargic and vomiting, stops eating, has yellow gums or eyes, unusual bleeding, or drinks and urinates much more or much less than usual.
Is the leptospirosis vaccine for dogs core or optional?
It depends on where you live. The World Small Animal Veterinary Association's 2024 vaccination guidelines say that where canine leptospirosis is endemic, the relevant strains are known and suitable vaccines exist, vaccinating all dogs is highly recommended and the vaccine should be considered core there.
The Toronto Humane Society describes it as non-core in the American Animal Hospital Association's scheme, but essential for dogs living in or travelling to areas where lepto is present. To judge your dog's risk, your vet may ask questions like these:
| Question | Why it matters |
|---|---|
| Do you live in a city with rats and raccoons? | These are the main carriers in southern Ontario |
| Does your dog drink from or swim in puddles, ponds or ditches? | Contaminated water is a common route |
| Do you hike, camp or visit the cottage? | More contact with wildlife habitats |
| Does your dog go to daycare, boarding or dog parks? | Shared outdoor spaces |
| Will you travel with your dog? | Risk varies by region |
How the lepto vaccine schedule works
The lepto vaccine starts with two doses given 2 to 4 weeks apart, the starting series the Toronto Humane Society describes, and then a booster every year. Merck says current vaccines give good protection for at least one year, and that older advice to vaccinate every 6 months is no longer justified.
Vaccines cover four strains, the serovars Canicola, Icterohaemorrhagiae, Grippotyphosa and Pomona, Merck notes, and the Toronto Humane Society says a four-serovar vaccine is the one recommended.
Because protection lasts about a year, the booster often lines up with your dog's annual checkup, while core vaccines like the DHPP vaccine may be spaced further apart. Missed a booster by a long way? Your vet may restart the two-dose series.
The Worms & Germs Blog calls vaccination the most important step owners can take, describing the vaccine as safe and effective, though no vaccine is 100% protective. Tell your vet about any reaction your dog has had to a past vaccine, and ask what to watch for in the day or two after the shot.
Other ways to lower the risk
Everyday habits lower the risk alongside the vaccine. Carry water on walks so your dog isn't tempted by puddles, ponds and ditches. Tip out standing water in your yard, and keep garbage and compost sealed so rats and raccoons have less reason to visit.
Wash your hands after cleaning up after your dog, especially if they're unwell. If your dog does get lepto, follow your vet's hygiene instructions at home to protect your family.
Keep vaccine dates in one place. The free PetGrid app stores them in your pet's health records and sends reminders when the yearly booster is due, and our dog and cat vaccine schedule for Canada shows where lepto fits.
Questions fréquentes
Does my dog need the lepto vaccine in Toronto?
Many Toronto dogs are at some risk, because rats and raccoons are thought to be the main carriers in southern Ontario. Ask your vet; WSAVA says the vaccine should be considered core where lepto is endemic.
How often do dogs need the leptospirosis vaccine?
Usually two first doses 2 to 4 weeks apart, then a booster every year. Merck says current vaccines protect for at least one year.
Can small dogs or indoor dogs get leptospirosis?
Yes, Merck notes that dogs of any age, breed or sex can be infected, and it isn't limited to large or outdoor dogs. A small dog walking in a city park can still meet contaminated urine or water.
Can people catch leptospirosis from dogs?
Yes, it can spread to people, though Merck says human infections aren't common. Hand washing and following your vet's hygiene advice lower the risk if your dog is ill.
What are the signs of leptospirosis in dogs?
Lethargy, vomiting, loss of appetite and changes in urination are common, and sudden kidney injury is the most frequent form, according to Merck. Yellow gums or eyes and bleeding can also happen; see a vet right away.
En bref
If you live in Ontario, city or country, the leptospirosis vaccine for dogs is worth a conversation with your vet. It starts with two doses, needs a yearly booster, and works best alongside small habits like keeping your dog out of puddles.
The PetGrid app is free for pet owners and keeps every vaccine date and reminder in one place, with any vet. Here's how the app works.
Gardez les dossiers, les vaccins et les visites de votre animal dans un seul endroit sûr. L'application PetGrid est gratuite pour les propriétaires d'animaux, avec ou sans clinique.
Get the free PetGrid appSources
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