2026 is on track to be one of the worst tick seasons Ontario has ever seen
It started early this year. Experts warned in April that tick season began weeks ahead of schedule across Canada, driven by a milder-than-average winter. The CDC reported that ER visits for tick bites are the highest for this time of year since 2017. And Public Health Ontario scheduled a dedicated session on tick-borne diseases for May 2026 — a sign that the public health community is paying close attention.
This isn’t a future problem. It’s happening right now, and if you’re a dog owner who walks trails, visits parks, or even has a backyard in the GTA — you and your dog are at risk.
The numbers are alarming
Canada recorded 5,239 Lyme disease cases in 2024 — the highest single year on record. That’s more than double the 2,525 cases reported just two years earlier. Ontario accounted for roughly half of all cases nationally, with a 27% increase over the previous year.
A decade ago, Canada was reporting fewer than 1,000 cases per year. The number has more than quintupled.
The trend isn’t slowing down. Climate change is pushing blacklegged tick populations northward at an estimated 46 kilometres per year, and areas that were considered low-risk five years ago now have established tick populations.
Where are the ticks in the GTA?
Confirmed Toronto hotspots
Toronto Public Health has identified several areas with high tick activity through surveillance:
- Rouge Park / Rouge National Urban Park (Scarborough) — the most well-documented hotspot in the city. Toronto Public Health has linked Lyme cases specifically to Rouge Valley.
- Morningside Park (Scarborough)
- Cedar Ridge Park (Scarborough)
- Algonquin Island (Toronto Islands)
Don Valley, Humber River, and the ravine system
Any neighbourhood bordering Toronto’s extensive ravine network presents elevated risk. That includes Leaside, East York, Don Mills, Moore Park, and other areas adjacent to the Don River valley. Toronto’s ravines cover roughly 17% of the city’s landmass — all of it potential tick habitat.
The Humber River valley corridor through Vaughan, Woodbridge, and Etobicoke is another risk zone, as is the Credit River corridor through Mississauga and Halton Hills.
York Region — Newmarket, Aurora, and surrounding areas
All of York Region is now classified as an estimated Lyme disease risk area by Public Health Ontario. This is an official designation, not speculation.
York Region Public Health confirms that blacklegged ticks have been found throughout the region — including Newmarket, Aurora, Stouffville, Markham, Richmond Hill, Vaughan, and Gormley — and some of those ticks have tested positive for Borrelia burgdorferi, the bacterium that causes Lyme disease.
The Lake Simcoe Region Conservation Authority, which manages trail systems in the Newmarket/Aurora area, has published dedicated tick guidance for their properties. Trails around Fairy Lake, Nokiidaa Trail, Sheppard’s Bush, and other green spaces in Newmarket and Aurora should all be treated as tick-risk areas.
The Oak Ridges Moraine — running through Richmond Hill, Caledon, and King City — is among the highest tick activity zones in the entire GTA.
If you live in Newmarket, Aurora, or anywhere in York Region and you walk your dog on trails, in conservation areas, or even in your backyard near wooded edges — tick prevention is not optional.
Know your ticks
Not all ticks carry Lyme disease. Two main species in Ontario:
Blacklegged tick (deer tick) — the dangerous one
The only tick in Ontario that transmits Lyme disease. Also carries anaplasmosis, babesiosis, and Powassan virus.
What it looks like: Nymphs are poppy-seed-sized (nearly invisible). Adults are sesame-seed-sized with a glossy black shield and reddish-orange abdomen.
When it’s active: Two peaks — spring nymphs (May–June) and fall adults (September–October). But adult blacklegged ticks are active on any day above 4°C — including warm days in December and March.
American dog tick — common but less dangerous
Larger, with distinctive cream/white mottling on the back. Does NOT carry Lyme disease.
Not sure what you found? Take a photo and submit it to eTick.ca — free tick identification.
How Lyme disease affects dogs
Here’s the scary part: most infected dogs show no symptoms at all. Your dog can be carrying Lyme disease for months without you knowing.
When symptoms do appear — typically 2 to 5 months after infection — they include:
- Shifting leg lameness (limping that moves between legs)
- Swollen, painful joints
- Fever and lethargy
- Loss of appetite
- Swollen lymph nodes
In some cases, Lyme disease can cause Lyme nephritis — a serious and potentially fatal kidney complication. Labrador Retrievers, Golden Retrievers, and Bernese Mountain Dogs appear to be more susceptible to this.
How it’s diagnosed
Most vets now include Lyme screening in the annual 4Dx blood test, which checks for Lyme disease, anaplasmosis, ehrlichiosis, and heartworm simultaneously. If your dog tests positive, a follow-up Quant C6 test measures the infection level.
Ask your vet about a 4Dx test at your dog’s next annual checkup. It’s the simplest way to catch an infection you’d otherwise never know about.
Prevention: what you should be doing right now
Tick prevention medication
Ontario vets recommend prescription oral chewables as the first line of defence:
- NexGard (monthly)
- Bravecto (one dose lasts 12 weeks)
- Simparica (monthly)
- Credelio (monthly)
All are prescription-only in Canada. Talk to your vet about which one is right for your dog.
Important: Ontario vets increasingly recommend year-round tick prevention, not just seasonal. Since blacklegged ticks are active on any day above 4°C, your dog can pick up a tick in December.
The Lyme vaccine for dogs
There is a vaccine available for dogs — it’s considered a non-core vaccine in Canada ($30–65 per dose). Given as 2 initial doses, 2–4 weeks apart, then annually.
Veterinary opinion is split on whether every dog needs it, but if your dog frequently visits ravines, conservation areas, trails, or off-leash parks near woodlands in the GTA, it’s worth discussing with your vet.
The vaccine is not 100% effective — tick prevention medication is still essential even with vaccination.
Post-walk tick checks
Check your dog immediately after every walk in a natural area. Focus on:
- Inside and behind the ears
- Around the eyes
- Under the collar
- Armpits (under front legs)
- Between the toes
- Around the tail and groin area
Run your hands over your dog’s entire body, feeling for small bumps. Brush your dog outdoors before going inside to knock off any crawling ticks that haven’t attached yet.
How to remove a tick
- Use fine-point tweezers or a tick removal tool.
- Grasp the tick as close to the skin as possible.
- Pull straight back with slow, steady pressure — do NOT twist or jerk.
- Clean the bite area with rubbing alcohol or soap and water.
- Save the tick in a sealed container — you can submit it to eTick.ca for identification or GeneeTicks for pathogen testing.
- Monitor your dog for symptoms over the following weeks.
See your vet if: the tick was attached for more than 24 hours, you can’t fully remove it, or your dog shows any symptoms in the following weeks.
The new treatments: what’s changed
Single-dose doxycycline — no doctor visit needed in Ontario
This is the most important thing for dog owners to know for themselves.
Since January 2023, Ontario pharmacists can prescribe a single 200mg dose of doxycycline directly — no doctor visit required. This must be taken within 72 hours of removing a high-risk tick bite (identified blacklegged tick, attached 36+ hours, in a risk area).
If you get bitten by a tick, save the tick, go to a pharmacy, and ask the pharmacist about post-exposure prophylaxis. You don’t need to wait for a doctor’s appointment.
Piperacillin — the breakthrough on the horizon
In April 2025, researchers at Northwestern University published a study in Science Translational Medicine showing that piperacillin — an existing FDA-approved antibiotic — cured Lyme disease in mice at 100 times lower dosage than doxycycline.
Why this matters:
- At such low doses, it had virtually no impact on gut bacteria — unlike doxycycline, which can wreck your microbiome.
- It could work for the 10–20% of patients where doxycycline fails.
- It’s safe for young children (doxycycline isn’t approved for young kids).
- It could potentially be used as a preventive treatment after a known tick bite.
Human clinical trials haven’t started yet, but this is the most promising Lyme treatment development in years.
A human Lyme vaccine is coming
Pfizer and Valneva announced Phase 3 trial results in March 2026 for their Lyme disease vaccine candidate (VLA15), showing 73.2% efficacy in preventing confirmed Lyme disease in people ages 5 and up.
This would be the first human Lyme vaccine in over 25 years — the last one (LYMErix) was pulled from the market in 2002. Pfizer plans to file for FDA approval in 2026, with a potential launch in the second half of 2027.
For dog owners who spend significant time on trails and in parks, this could be a game-changer.
Don’t forget: you’re at risk too
You’re spending time in tick habitat every day walking your dog. During walks:
- Wear light-coloured clothing (easier to spot ticks).
- Tuck pants into socks when walking trails.
- Use DEET or icaridin-based repellent on exposed skin.
- Stay on the center of trails — avoid brushing against trailside vegetation.
After walks:
- Full body check — especially groin, armpits, scalp, behind ears, and behind knees.
- Shower within 2 hours (shown to reduce Lyme risk).
- Tumble dry clothing on high heat for 60 minutes before washing — this kills ticks hiding in fabric.
The bottom line
Ticks aren’t going away. The populations are expanding, the season is getting longer, and the GTA is firmly in the risk zone — especially if you’re in York Region, near Toronto’s ravine system, or anywhere near wooded trails.
Three things you should do this week:
- Talk to your vet about year-round tick prevention medication and the Lyme vaccine.
- Start doing tick checks after every walk — on your dog and on yourself.
- Know that Ontario pharmacists can prescribe doxycycline after a tick bite. Save the tick, go to a pharmacy within 72 hours.
Ticks are a reality of dog ownership in Ontario now. The good news is that with the right prevention, you and your dog can still enjoy every trail, park, and off-leash adventure — you just need to be smart about it.
K9 Academy operates out of Leaside (Toronto) and Stouffville — two areas surrounded by the trails and green spaces where tick awareness matters most. If you’re looking for obedience training that happens in real-world environments, check out our group classes or call us at 437-778-5273.
Resources
- eTick.ca — Free tick identification by photo
- Public Health Ontario Vector-Borne Disease Tool — Interactive tick surveillance map
- City of Toronto — Lyme Disease
- York Region — Lyme Disease
- Parks Canada — Ticks in the Rouge
- Ontario.ca — Tick-Borne Diseases