How Often to Deworm a Dog: Worms, Heartworm, Fleas and Ticks

Intestinal worms

Intestinal parasites (roundworms, hookworms, whipworms, tapeworms, giardia) are very common, and some can spread to people, especially children. Here's the CAPC schedule:

Stage	How often
Puppies up to 8 weeks	Every 2 weeks, starting at 2 weeks of age
Puppies 2 to 6 months	Monthly
Adult dogs	Year-round monthly prevention that includes intestinal worms (many heartworm preventives do), or treatment at least 4 times a year
Fecal tests	At least 4 times in the first year, then at least twice a year in adults

Higher-risk dogs, such as those that hunt or eat prey, raw food or garbage, live with young children or people with weak immune systems, or often visit dog parks, daycare or boarding, may need more frequent checks.

Heartworm

Heartworm is spread by mosquitoes and has been diagnosed in all 50 states. The American Heartworm Society recommends its "think 12" rule: give a heartworm preventive 12 months a year and test your dog every 12 months. Puppies should start a preventive no later than 8 weeks of age. Prevention is far cheaper and safer than treatment: read heartworm disease in dogs.

Fleas and ticks

Fleas cause itching and allergies and can transmit tapeworms; ticks transmit diseases like Lyme disease, ehrlichiosis, anaplasmosis and Rocky Mountain spotted fever. CAPC recommends protection all year. Learn how to remove a tick and what to watch for in ticks on dogs.

Product	Usually lasts	Pros	Cons
Chewable tablet	1-3 months	Not affected by baths or swimming; some combine heartworm, worms, fleas and ticks	Doesn't repel: the parasite has to bite
Spot-on (topical)	About 1 month	Some repel ticks and mosquitoes	Must remember monthly; avoid bathing right before and after
Collar	Up to 8 months	Convenient, long-lasting	Can irritate the skin; check the fit
Heartworm injection	6 or 12 months	No monthly dose to forget	Given only at the vet; doesn't cover fleas or ticks

Important: dog flea and tick products containing permethrin are highly toxic to cats. If you have cats, ask your vet which product to use, and never use a dog product on a cat.

How much parasite prevention costs per year

According to Rover's 2026 cost survey, flea, tick and heartworm prevention costs about $295-$360 a year for an adult dog, depending on weight and product. Add the yearly heartworm test (about $71) and fecal tests (about $58 each) at your checkup (Synchrony/CareCredit 2025-2026 cost study). We include it in the annual cost of owning a dog.

Prices vary a lot with your dog's weight and the brand. Your vet can tell you which product fits your area and your dog's lifestyle.

Signs your dog may have parasites

Diarrhea, vomiting or stool with mucus (see dog has diarrhea and won't eat).
Visible worms in the stool, or "rice grains" around the bottom (tapeworms).
Scooting on the floor.
A pot belly in puppies.
Itching, visible fleas or ticks.
A soft cough and tiring easily (possible heartworm).

Frequently asked questions

Can you deworm a dog too often?

Approved parasite products are safe at the labeled dose, but there's no point giving them more often than needed. Ideally, your vet tailors the schedule to your dog's lifestyle.

Should I deworm my puppy before vaccines?

Yes, puppies are usually dewormed on the same visits as their vaccines, following the every-2-weeks schedule early on.

Do indoor dogs need parasite prevention?

Yes. Mosquitoes get indoors, fleas hitch a ride on people and other pets, and dogs still go outside to potty. Heartworm prevention is recommended year-round for all dogs.

Sources

This article is for general information and does not replace diagnosis or treatment by a veterinarian. If you are worried about your pet's health, call your vet clinic.