Flea and Tick Prevention for Dogs in the US

Q: Do dogs in the US need flea and tick prevention in winter?

The Companion Animal Parasite Council recommends year-round flea and tick control for dogs, for life. It says blacklegged tick adults are most active in cooler months, so stopping in winter can leave a gap. The FDA notes that fleas can live indoors year-round in a warm house, and that outdoor flea season is longer in some states than others. Ask your vet what fits your county.

Q: Can my dog give me Lyme disease?

The CDC and Cornell both say people do not catch Lyme disease directly from a dog. Dogs and people are infected by blacklegged ticks. A dog can carry those ticks into the house or yard. Cornell says most dogs exposed to Lyme do not become sick. If your dog is lame, feverish, or suddenly very unwell, ask your vet.

Q: Are oral flea and tick medicines safe for senior dogs?

The FDA says isoxazoline products are safe and effective for the majority of dogs and cats, and also that neurologic events, including seizures, have occurred, including in animals with no prior seizure history. The FDA tells owners to consult a veterinarian, and to talk with a vet before using any flea or tick product on a dog who is old, sick, medicated, pregnant, or nursing. This page cannot tell you which product is safe for your dog.

Q: Does a Lyme vaccine replace tick prevention?

No. Cornell and the Companion Animal Parasite Council both say a Lyme vaccine does not replace tick control. Ticks carry more than Lyme disease, and the vaccine does not stop a tick attaching. Ask your vet whether vaccination fits your dog's location and lifestyle, and keep using the preventive your vet recommends.

The tick in a Massachusetts woods is not the tick in an Arizona backyard. US prevention starts with which parasites actually live where you walk, then with a product your vet says matches your dog.

This page summarizes what the CDC, the FDA, Cornell University College of Veterinary Medicine, and the Companion Animal Parasite Council (CAPC) publish for dog owners. It is not veterinary advice, and it does not name a best product. If your dog is senior, epileptic, pregnant, nursing, or on other medicines, ask your vet before you use anything. The FDA says to have that conversation for old, weak, medicated, sick, pregnant, or nursing pets, even if a previous dose seemed fine.

A UK reader should use flea, tick and worm treatment for dogs. Lungworm and the UK product market are a different article. This page is about the United States.

Fleas are not only a warm-weather problem

The FDA says flea bites can trigger flea allergy dermatitis, and that a severe infestation can lead to anemia and, rarely, death, because fleas feed on blood. Pets can also bring ticks indoors.

CAPC's flea guidelines say all dogs should be treated year-round, for life, with flea-control products, to limit fleas on the dog and stop a population establishing in the home. Once an infestation is established, CAPC says it may take several months to control, and every pet in the home has to be treated. Fleas also spread pathogens to people, including the tapeworm Dipylidium caninum if a flea is swallowed.

The FDA's consumer page adds the climate detail. Outdoor flea season peaks in warm months and is short in a cold climate, on the order of four months in some places, and year-round in places like Florida. Fleas can live inside a warm house year-round wherever you live. CAPC's general guidelines also call for year-round parasite control that covers heartworm, intestinal parasites, fleas, and ticks. Heartworm is outside the scope of this page. Ask your vet about it at the same visit. CAPC treats it as part of the same routine.

Which ticks live where

The CDC's where-ticks-live page maps ticks that transmit disease to people in the contiguous United States. It says a tick's presence on a map is not the same thing as a disease risk in that county, and it tells readers to check a local health department. Naturally occurring populations of the ticks it describes do not occur in Alaska. The brown dog tick does occur in Hawaii.

The table is a reading aid, not a diagnosis. Pathogen names below are the ones the CDC lists for people. Dogs are not at equal risk from every one of those pathogens. Ask your vet what is worth testing for where you live. CAPC publishes prevalence maps that change over time. Use the current map rather than a percentage remembered from an article. On a small screen, swipe the table sideways to see every column.

Tick	Where the CDC says it is found	What the CDC says it can transmit to people
Blacklegged tick (Ixodes scapularis), also called the deer tick	Widely across the eastern United States. Adults may seek a host whenever winter temperatures are above freezing. Greatest bite risk is spring, summer, and fall.	Lyme disease (Borrelia burgdorferi and B. mayonii), anaplasmosis, babesiosis, hard-tick relapsing fever, one form of ehrlichiosis, and Powassan virus disease.
Western blacklegged tick (Ixodes pacificus)	Along the Pacific coast, particularly northern California.	Lyme disease (Borrelia burgdorferi), anaplasmosis, and hard-tick relapsing fever.
American dog tick (Dermacentor variabilis and D. similis)	D. variabilis is widely east of the Rockies, with limited areas west. D. similis is west of the Rockies. The CDC says more research is needed on how these species spread disease.	Tularemia and Rocky Mountain spotted fever. The CDC's Lyme page says this tick cannot transmit Lyme disease bacteria.
Lone star tick (Amblyomma americanum)	Widely in the Northeast, South, and Midwest.	Human ehrlichiosis (Ehrlichia chaffeensis and E. ewingii), tularemia, Heartland virus, and Bourbon virus. The CDC also notes STARI, a circular rash of unknown cause, and growing evidence that alpha-gal syndrome may follow a bite. It cannot transmit Lyme disease bacteria.
Brown dog tick (Rhipicephalus sanguineus)	Worldwide. Dogs are the primary host at every life stage. The tick may also bite people.	Rocky Mountain spotted fever in the southwestern US and along the US–Mexico border. Not a Lyme vector.
Gulf Coast tick (Amblyomma maculatum)	Primarily the Southeast, with focal populations in the Northeast, Midwest, and Southwest.	Rickettsia parkeri rickettsiosis, a form of spotted fever.
Rocky Mountain wood tick (Dermacentor andersoni)	Rocky Mountain states and southwestern Canada, at elevations of about 4,000 to 10,500 feet.	Rocky Mountain spotted fever, Colorado tick fever, and tularemia. Not a Lyme vector.
Asian longhorned tick (Haemaphysalis longicornis)	First reported in the United States in 2017. The CDC's page, noting finds as of April 12, 2024, lists a growing set of eastern and midwestern states and points to the USDA map. Females can reproduce without mating, so numbers on one animal can be high.	The CDC says this tick appears less attracted to people than the blacklegged, lone star, and American dog ticks. A laboratory study found it is not likely to spread Lyme disease bacteria in the US. It can carry the Rocky Mountain spotted fever bacterium in the lab. The CDC says that bacterium had not yet been found in these ticks in nature, and that research is ongoing.

The CDC's Lyme page says infected ticks are found most commonly in forested areas of the northeastern, north-central, and mid-Atlantic states, and in smaller areas of Pacific Coast states. The share of ticks that are infected ranges from none to over 50 percent, depending on the area and the life stage of the tick. Do not turn that range into a rate for your county.

Lyme disease in dogs

Cornell's Lyme disease page says the infection is caused by Borrelia burgdorferi inside the blacklegged tick, and that it is most common in the Northeast, mid-Atlantic, and upper Midwest, with the range increasing. Ticks can be active year-round when the temperature is above 40°F.

Cornell says that after an infected tick attaches, it takes at least 24 to 48 hours before transmission occurs, so prompt removal matters. The CDC's figure for people is "more than 24 hours." Use Cornell's 24 to 48 hours when the patient is the dog. Removal, as Cornell describes it, means grasping the tick close to the skin with tweezers or a tick-removal device and pulling with slow, steady traction. If you are unsure, ask your vet rather than trying a home remedy.

Most dogs who are exposed do not become sick, Cornell says. When they do, signs often wait 2 to 5 months after the bite. The common signs Cornell lists are fever, lameness, lethargy, a smaller appetite, swollen or painful joints, and swollen lymph nodes. A less common complication, Lyme nephritis, damages the kidneys. Cornell says it may be more likely in young to middle-aged retrievers, and that those dogs can be much more ill: vomiting, not eating, drinking and urinating more, weight loss, extreme lethargy. Many dogs with Lyme nephritis do not survive. That is a reason to call a vet quickly when a dog is very unwell. It is not a diagnosis you can make from a webpage, and this page does not describe treatment. Cornell says sick dogs are treated by a veterinarian, commonly with antibiotics, and that the drug and the plan are the vet's decision.

People do not catch Lyme from the dog. The CDC and Cornell both say that. The shared risk is the tick. A dog who is not on tick control can bring infected ticks into the house. The CDC says to consider tick-prevention products for pets for that reason. Cornell says to check both of you after time in tall grass, woods, or leaf litter, and that short lawns and cleaned-up leaf piles reduce backyard exposure.

Prevention, in Cornell's list, is year-round tick control, routine checks, prompt removal, avoiding high-risk vegetation, and vaccination where it fits. Tick control is the most important item, and it has to be used consistently. Collars, topical products, and chewables all exist. Your vet chooses among them. Cornell says a previous infection does not leave natural immunity. Ask your vet whether the Lyme vaccine fits your dog's location and lifestyle. Even with a vaccine, Cornell says preventives should still be used year-round.

CAPC's Lyme guidelines match that last point. Vaccination does not replace tick control, because vaccines may not cover every strain and ticks carry other pathogens that have no vaccine. CAPC recommends year-round acaricides with residual activity. Its blacklegged-tick page adds a seasonal warning: adult blacklegged ticks are most likely to feed on dogs and cats in the cooler months, so stopping tick control for winter is the gap, not the safe pause. CAPC's general guidelines say to vaccinate against Borrelia burgdorferi where Lyme is endemic or emerging. That is CAPC's recommendation to veterinarians. The decision for your dog is still a conversation with your vet.

Brown dog ticks can move in

CAPC's tick guidelines say all dogs should be on tick-control products year-round, for life, partly because brown dog ticks can establish inside a home or kennel in any month. Once they have, CAPC says control can take several months, the pets have to stay on a product, and a licensed exterminator is needed to clear the building. Seasonal or reactive treatment often starts after the ticks are already active.

Product types, and who regulates them

The FDA's consumer page lists the forms you will see: pills and chews, collars, sprays, dips, shampoos, powders, and spot-ons. Some products are sold only by a veterinarian. Others are over the counter. Side effects happen. The FDA says products have been used in millions of pets and adverse events still occur, including, in some animals, seizures and death. Read the current label every time. Directions change. Match the species, the life stage, and the weight. If the product is for dogs, do not use it on a cat. Do not treat a puppy unless the label allows that age and weight. If you use a spray or spot-on and you have more than one pet, keep them apart until the product is dry so one does not lick it off another. That matters most when the product is only for dogs and a cat lives in the house.

The FDA's isoxazoline fact sheet is the specific warning for a class of oral and topical drugs that includes products sold under names such as Bravecto, NexGard, Simparica, and Credelio. The FDA considers the class safe and effective for the majority of dogs and cats. It also says the class has been associated with neurologic events, including muscle tremors, ataxia, and seizures, and that seizures may occur in an animal with no prior history. Some products in the class are also approved for other parasites, including, for a few of them, heartworm prevention. The fact sheet says some flea and tick products are regulated by the FDA and some by the Environmental Protection Agency (EPA). The format does not tell you which. The label does. Discuss the options with your vet.

A botanical spray is a different kind of product from an acaricide CAPC describes as having residual activity and a label claim against Ixodes ticks. This page does not claim that a plant-based spray works, and it does not claim that it does not. Read the label and ask your vet. "Natural" is not a regulatory category on the FDA fact sheet.

A GPS collar is not a preventive either. Knowing where a dog walked can help you describe the habitat to your vet. It does not kill a flea or a tick.

Age does not retire the need. CAPC says flea and tick control is for the life of the dog. The FDA says old dogs are exactly the group to clear with a veterinarian first. A senior dog who is stiff, on pain medicine, or epileptic needs that conversation, not a product picked from a shelf. Our senior-signs page is about recognizing aging. It is not a dosing chart.

Questions worth asking your vet

Which ticks are a real concern in this county, and do we need a Lyme vaccine as well as a preventive? CAPC's maps are a starting point. Your vet has the local picture.
Does this product have a label claim against the ticks we actually have, and how long does the label say it lasts?
Is it FDA-regulated or EPA-regulated, and is the dose right for this dog's current weight?
Is an isoxazoline appropriate given this dog's seizure history, age, and other drugs?
If a cat lives here, is this product safe to have in the same house?
What should I do if I see vomiting, wobbliness, tremors, or a seizure after a dose? The FDA says to call your veterinarian. For a collar, remove it. Do not wait out a bad reaction because a webpage listed it as uncommon.

The product links below are labeled as ads. They stay hidden until a real web address is added. They are not a statement that the product prevents fleas or ticks. See our affiliate disclosure.

A plant-based flea and tick brandAd

Reserved link for a US botanical flea and tick brand. Not a recommendation, and not a claim that it replaces a product your vet has chosen.

Product link

A GPS collar, not a preventiveAd

Reserved link for a US dog-collar tracker. A collar that logs location does not kill fleas or ticks.

Collar link

Common questions

Do dogs in the US need flea and tick prevention in winter?

CAPC says yes: year-round, for life, and it singles out winter as the season when blacklegged adults are most active. The FDA says indoor fleas do not follow the outdoor season, and that outdoor season length depends on where you live. Ask your vet before you skip a month.

Can my dog give me Lyme disease?

Not directly. The CDC and Cornell say people get Lyme from blacklegged ticks, not from the dog. The dog can carry those ticks inside. Cornell says most exposed dogs never get sick. Lameness, fever, or a dog who is suddenly very ill is a reason to call your vet.

Are oral flea and tick medicines safe for senior dogs?

The FDA says the isoxazoline class is safe and effective for most dogs, and that tremors, ataxia, and seizures have been reported, including in dogs with no seizure history. It tells you to ask a veterinarian, and its consumer page says to ask before using products on an old or sick dog. This page will not pick a product for you.

Does a Lyme vaccine replace tick prevention?

No. Cornell and CAPC both say the vaccine does not replace tick control. Ticks transmit more than Lyme. Ask your vet whether vaccination belongs in your dog's plan on top of a preventive, not instead of one.

How old is your dog in human years?

Age does not cancel flea and tick risk. The calculator shows when this site would call your dog a senior, which is a useful prompt to ask your vet before the next dose.

Go to the calculator