Lyme season in the Northeast: what tick months mean for your dog

In the US Northeast, Lyme season has two peaks: April to June, when tiny nymph ticks are most active, and September to November, when adult ticks take over. The risk is lower but real through the rest of the year, so parasite control guidelines recommend tick protection all year, plus the Lyme vaccine for dogs in high-risk areas.

Use the calendar above to see the tick months for the United States and other countries.

If you walk a dog in Connecticut, Pennsylvania or Wisconsin, the question is not whether Lyme disease is around. It is which months carry the most risk, and what your dog’s protection should look like before they arrive.

Where Lyme disease is common

Lyme disease is carried by blacklegged ticks, and those ticks are not spread evenly across the United States. The national surveillance report for 2022 names the high-incidence jurisdictions, almost all of them in the Northeast, the mid-Atlantic and the upper Midwest: Connecticut, Delaware, the District of Columbia, Maine, Maryland, Massachusetts, Minnesota, New Hampshire, New Jersey, New York, Pennsylvania, Rhode Island, Vermont, Virginia, West Virginia and Wisconsin.

Outside those states the risk is lower but not zero, and the tick’s range has been widening for years. The honest answer to “is Lyme a concern for my dog?” starts with where you live, then with the month.

When ticks are most active

Blacklegged ticks feed in every stage of their life, but the stage that infects most dogs is the nymph: the size of a poppy seed, easy to miss, and most active from roughly May to July in the Northeast. Adult ticks take over in autumn and stay active on any day above about 4 °C (39 °F), which is why a mild November walk through leaf litter is not as safe as it feels.

This is the tick risk in the US Northeast by month, from the regional risk calendars in Maggie, which a vet reviewed:

So the Lyme calendar in a high-incidence state has two peaks, spring to early summer and autumn, with a thinner but real risk through the rest of the year. The Companion Animal Parasite Council recommends year-round tick control for these ticks, not a summer-only course.

Why speed matters

A tick does not pass Lyme disease on the moment it bites. CAPC notes that an infected tick usually has to feed for about 24 to 48 hours first. That window is the reason both daily checks and a fast-acting tick product work. A tick that is killed or removed before it has fed for a day or more is far less likely to pass the infection on.

What prevention looks like

• Tick control every month, all year. A monthly or long-acting tick preventive is the first line. Our flea and tick schedule post covers the products and intervals, and has a calculator for the next dose.
• The Lyme vaccine, where the risk is real. It is not a core vaccine for every dog in the country. Veterinary guidelines recommend it for dogs living in or travelling to areas where the disease is established or emerging. The first course is two doses two to four weeks apart, then one booster each year, timed to land before the spring peak. The vaccine does not replace tick control, because ticks carry other diseases too.
• Check after walks. A tick removed within a day has had little chance to transmit anything.
• Know the signs. See the section below.

How to check your dog after a hike

Do the check before your dog comes inside, and use your fingertips. Nymphs are small enough that you feel them sooner than you see them.

1. Head. Ears inside and out, around the eyes and lips, and under the collar.
2. Legs and feet. Armpits, the inside of the back legs, and between every toe.
3. Body. Belly, groin and the base of the tail.

If you find a tick, remove it with a tick hook or fine tweezers close to the skin, without squeezing the body. Write down the date and where you walked.

Signs of Lyme disease in dogs

The Merck Veterinary Manual notes that many infected dogs show no signs at all. When signs do appear, often weeks after the bite, look for:

• lameness that shifts from one leg to another
• fever
• swollen or painful joints
• loss of appetite and lethargy

Kidney involvement is rarer and serious. Any of these in a dog from a tick area deserves a vet visit, with the tick exposure mentioned.

Where Maggie fits

Maggie reads the Lyme risk from your state, not from the country as a whole. A dog in New York sees the Lyme vaccine on the schedule as a recommended vaccine, and a tick-season alert from March, before the spring peak; a dog in Florida does not see the vaccine, because the risk there does not justify it. If the state is not set yet, the vaccine shows under “Depends on where you live” rather than disappearing. Tick preventive doses you log count towards cover in the risk profile, so a missed month shows as a gap, not as silence. The dog vaccine schedule post explains how the rest of the schedule is built, and autumn tick season covers why the second peak catches owners out.

Leo is an AI companion, not a veterinarian. For medical concerns, always consult your vet.