When to Start Tick Prevention: A State-by-State Guide

Most people start tick prevention too late

The mistake is almost always the same. Owners wait until they see a tick on their dog, or until the weather feels like spring, and by then ticks have already been active for weeks.

Ticks don't follow the calendar. They follow temperature and humidity. In much of the US, they're active anytime it's above about 40°F, which in a surprising number of states means year-round. And the diseases they carry are serious. Lyme disease cases in dogs have been climbing for two decades, and anaplasmosis and ehrlichiosis now have confirmed cases in nearly every state.

Here's when to start prevention depending on where you live.

Tick season isn't what you think

The old rule was "April through October." That rule is wrong pretty much everywhere now.

Adult blacklegged ticks (the ones that carry Lyme) are actually most active in the fall and early spring, not summer. They don't die in winter; they just slow down. On any day above freezing, especially after a warm spell, they come right back out.

CDC tick distribution maps now show at least one disease-carrying species in every contiguous state. Some states have four or more. And the Companion Animal Parasite Council forecast projects high tick activity well into months that used to be considered safe.

The safe default in 2026 is year-round prevention. The question isn't really when to start. It's whether you can skip a few months based on your climate.

Southeast and Gulf Coast: year-round, no exceptions

Florida, Georgia, Alabama, Mississippi, Louisiana, South Carolina, Texas. You don't get a break here. Winters are too mild to kill off ticks, and the lone star tick, brown dog tick, and Gulf Coast tick are all active every month.

If you're in this region, your dog should be on prevention 12 months a year. Starting late or skipping a dose can leave a window that ticks absolutely will exploit.

Northeast: start by March, consider year-round

The Northeast has the highest Lyme disease rates in the country. Connecticut, Massachusetts, New York, New Jersey, Pennsylvania, Rhode Island, Vermont, New Hampshire, and Maine all sit in the thick of blacklegged tick territory.

Prevention should be in place by early March. Adult ticks come out on the first warm days of late winter, often before the snow has fully melted. Waiting until April means missing the first wave.

Most vets in this region now recommend year-round prevention rather than seasonal. The winters have been too inconsistent for the seasonal approach to be reliable.

Mid-Atlantic and Upper South: start by March

Virginia, Maryland, Delaware, North Carolina, Tennessee, Kentucky, West Virginia. Similar pattern to the Northeast but with a slightly longer active season on the back end.

Start prevention by the first week of March. Don't stop until at least mid-December, and year-round is the safer choice.

Midwest: start by April

Ohio, Indiana, Illinois, Michigan, Wisconsin, Minnesota, Iowa, Missouri. Tick activity ramps up sharply through April as temperatures climb.

April 1 is a reasonable start date for most of the Midwest, though the southern parts of Missouri and Illinois should start in March. Wisconsin and Minnesota in particular have seen rapid expansion of the blacklegged tick. Lyme disease cases have more than doubled in both states over the last decade.

Great Plains and Mountain West: start by April or May

Kansas, Nebraska, the Dakotas, Montana, Wyoming, Colorado, Idaho, Utah. Tick pressure is lower here than in the East, but it's far from zero. The American dog tick and Rocky Mountain wood tick are the main concerns.

Start prevention in April for the plains states, May for higher-elevation areas in the Mountain West. If your dog hikes, hunts, or spends time in tall grass, don't wait. Start in March to be safe.

Pacific Northwest: start by March

Western Oregon and Washington have milder, wetter winters than most of the country, which means ticks stay active on and off through the cold months. The western blacklegged tick is the main Lyme carrier here.

Start prevention by March. East of the Cascades, where it's drier and colder, April is usually fine.

Southwest: depends on elevation

Arizona, New Mexico, Nevada, Southern California. This region is tricky because it varies so much by elevation and local climate.

• Low desert (Phoenix, Tucson, Las Vegas, LA basin): brown dog ticks are active year-round. Go year-round.
• Higher elevations (Flagstaff, Santa Fe, Reno): April to October is usually enough.

The brown dog tick is the one to watch here. It's the only tick that readily infests indoor spaces, so even apartment dogs can get them.

The state-by-state quick reference

These dates are conservative starting points. If your dog spends a lot of time in wooded areas, tall grass, or near deer trails, shift earlier by two to four weeks.

What kind of prevention to use

There are three main categories, and none of them is objectively the best. It depends on your dog and your situation.

• Oral chewables: monthly or every-3-month tablets. Easy to give, no residue, works for dogs that swim often. Popular options include isoxazoline-class products.
• Topical spot-ons: monthly liquid applied between the shoulder blades. Effective but can wash off with frequent swimming or bathing.
• Collars: last 6 to 8 months. Low-maintenance, but some dogs don't tolerate them.

Talk to your vet about which one fits your dog. The AVMA has a good overview of the tradeoffs. The important thing is that it's given on time, every time. Skipping doses is what creates exposure windows.

What if you're already late?

If your dog hasn't had prevention yet this year and you're reading this in April or May, start now. Don't wait for a "clean" month. Most oral and topical products start working within 24 hours, and the sooner you close the gap, the better.

Also do a thorough tick check. Part the fur on the ears, neck, armpits, groin, and between the toes. Any tick you find should be removed promptly with fine-tipped tweezers. Pull steady and straight, don't twist. If your dog shows signs of tick-borne illness in the following weeks (lethargy, limping that moves between legs, loss of appetite, fever), see your vet and mention the recent tick exposure.

How to not miss a dose

Monthly prevention only works if you actually remember to give it. One missed dose in May can mean an infection in June.

Pet Care Reminder sends reminders for monthly preventatives and logs each dose as you give it. You can see at a glance the last time your dog got their flea and tick treatment, which matters when a vet asks. The AKC notes that missed or late doses are one of the most common reasons prevention fails, and it's the easiest failure mode to eliminate.

Set it once, and stop worrying about whether this month's dose was the 7th or the 14th.

Sources

1. CDC: Regions Where Ticks Live. Maps of which tick species are established in each US state.
2. CDC: Lyme Disease Data and Statistics. Annual case counts by state and long-term trends.
3. CAPC Parasite Prevalence Maps. Companion Animal Parasite Council county-level forecasts for tick-borne disease in dogs.
4. AVMA: External Parasites. American Veterinary Medical Association overview of tick prevention products and strategies.
5. AKC: When Is Tick Season?. American Kennel Club regional guidance on tick activity and prevention timing.