The Companion Animal Parasite Council, which writes the parasite guidelines American vets follow, puts the baseline in one line: year-round broad-spectrum parasite control against heartworm, intestinal parasites, fleas and ticks. Where the dog lives and how it lives come after that: the council tells vets to fit the plan to the parasites found locally and to each pet's lifestyle.
The American Heartworm Society says heartworm has been diagnosed in all 50 states, and because infected mosquitoes can come inside, both outdoor and indoor pets are at risk. Its advice is to think 12: a heartworm test every 12 months and prevention 12 months a year. A dog over 7 months of age that is not already on prevention needs a test before starting. Every heartworm product on this page says the same on its label, and several add that the product does not kill adult heartworms.
Fleas and ticks are year-round too. The parasite council says every pet in the home is treated for fleas, and every dog gets tick control all year, throughout its life. Petipedia's page on fleas that keep coming back has why a flea treatment can look like it failed when it has not.
The council also calls for stool tests: at least four in a puppy's first year, and at least two a year in an adult dog.
The parasite council publishes maps of positive test results by state and county, for dogs and cats in the United States and Canada, from IDEXX and ANTECH laboratory data. They include heartworm, the tick-borne diseases Lyme, ehrlichiosis and anaplasmosis, and hookworms, roundworms and whipworms. The council notes the data cover less than 30 percent of the testing in each area, so a county with few positive tests may still have more cases than the map shows. The maps are on its site for owners, Pets and Parasites.
The council says lone star and black-legged ticks are most often found in the undergrowth and leaf litter of wooded areas that wildlife uses. Six products on this page carry a label claim to prevent infection with the Lyme bacterium by killing black-legged ticks: NexGard, NexGard PLUS, Simparica, Simparica Trio, Credelio and Credelio Quattro.
Dogs get the Taenia tapeworms by eating infected rabbits, rodents and other animals, and the council's advice is a leash or a fenced yard. Of the products here, only Interceptor Plus and Credelio Quattro treat tapeworms other than the flea tapeworm.
The Seresto collar's label cuts its protection to 5 months for fleas and 7 months for ticks in a dog that swims once a month or more, and says not to bathe the dog more than once a month to keep the full 8 months.
The EPA says never to put dog products on cats. The K9 Advantix II label says do not use on cats, it may be fatal, and to keep cats away from treated dogs for 24 hours. The labels of Frontline Plus for Dogs and Advantage Multi for Dogs also say not to use them on cats.
NexGard, NexGard PLUS, Simparica, Simparica Trio, Credelio, Credelio Quattro and every Bravecto product belong to one drug class, the isoxazolines. Each of their labels says the class has been associated with tremors, loss of coordination and seizures, that seizures have been reported even in dogs with no history of them, and to use them with caution in a dog with a history of seizures or neurologic disorders. The FDA adds that they can and have been used safely in the majority of dogs and cats, and asks owners to go through the dog's medical history with the vet first.
The labels start at different ages: 6 weeks for Heartgard Plus, Interceptor Plus and Revolution; 7 weeks for Advantage Multi, K9 Advantix II and the Seresto collar; 8 weeks for NexGard, NexGard PLUS, Simparica Trio, Credelio, Credelio Quattro, Trifexis, Bravecto 1-Month and Frontline Plus; 6 months for Simparica, Bravecto chews and topical, Bravecto Quantum and ProHeart 6; and 12 months for ProHeart 12.
Three products here are injections given at the clinic: ProHeart 6 and ProHeart 12 for heartworm, and Bravecto Quantum for fleas and ticks.
Every line below is from the product's own US label, linked on each card. Coverage here means the parasites the label names, nothing more. Doses come from the vet.
Show the products whose label covers all of these:
These are approved by the FDA as animal drugs. Each label says federal law restricts it to use by or on the order of a licensed veterinarian.
A chew once a month. From 8 weeks of age and 4 pounds.
It covers fleas and six ticks: black-legged (deer), American dog, lone star, Gulf Coast, brown dog and longhorned. The label also says it prevents infection with the Lyme bacterium by killing black-legged ticks.
It does not cover heartworm or intestinal worms.
The label, updated July 2026 · Petipedia: What is NexGard?
A chew once a month. From 8 weeks of age and 4 pounds.
It covers heartworm, roundworms, hookworms, fleas and the same six ticks as NexGard, with the same Lyme claim.
It does not cover whipworms or tapeworms.
For heartworm, the label says to keep giving it once a month for at least six months after the last exposure to mosquitoes.
The label, updated April 2026
A chew once a month. From 6 months of age and 2.8 pounds.
It covers fleas and six ticks: black-legged (deer), American dog, lone star, Gulf Coast, brown dog and longhorned. The label also says it prevents infection with the Lyme bacterium by killing black-legged ticks.
It does not cover heartworm or intestinal worms.
The label says it should not be used in dogs under 6 months of age.
The label, updated December 2024
A chew once a month. From 8 weeks of age and 2.8 pounds.
It covers heartworm, roundworms, hookworms, fleas and the same six ticks as Simparica, with the same Lyme claim. It also prevents the flea tapeworm by killing the fleas that carry it.
It does not cover whipworms, or the tapeworms dogs catch by eating rabbits, rodents and other animals.
The label, updated May 2025 · Petipedia: What is Simparica Trio?
A chew once a month, given with food. From 8 weeks of age and 4.4 pounds.
It covers fleas and five ticks: lone star, American dog, black-legged (deer), brown dog and longhorned. The label also says it prevents infection with the Lyme bacterium by killing black-legged ticks.
It does not cover heartworm or intestinal worms.
The label, updated May 2026 · Petipedia: What is Credelio?
A chew once a month. From 8 weeks of age and 3.3 pounds. Approved by the FDA in October 2024.
It covers heartworm, roundworms, hookworms, fleas, the same five ticks as Credelio with the same Lyme claim, and three tapeworms: the flea tapeworm and two that dogs catch by eating rabbits or livestock.
It does not cover whipworms.
The label, updated June 2026 · Petipedia: What is Credelio?
One chew every 12 weeks. From 6 months of age and 4.4 pounds.
It covers fleas and the black-legged (deer), American dog, brown dog and Asian longhorned ticks for 12 weeks, and the lone star tick for 8 weeks. The label allows a dose every 8 weeks where lone star ticks are a risk.
It does not cover heartworm or intestinal worms, and its label has no Lyme claim.
The label, updated October 2024 · Petipedia: What is Bravecto?
A chew once a month. From 8 weeks of age and 4.4 pounds, and from 6 months for the lone star tick.
It covers fleas and the black-legged (deer), American dog, brown dog, Asian longhorned and lone star ticks for a month.
It does not cover heartworm or intestinal worms, and its label has no Lyme claim.
The label, updated August 2026 · Petipedia: What is Bravecto?
Put on the skin every 12 weeks. From 6 months of age and 4.4 pounds. The label says the vet or a vet technician should show you how before the first dose.
It covers fleas and the black-legged (deer), American dog and brown dog ticks for 12 weeks, and the lone star tick for 8 weeks.
It does not cover the longhorned tick, heartworm or intestinal worms, and its label has no Lyme claim.
The label, updated August 2026 · Petipedia: What is Bravecto?
A chew once a month. From 6 weeks of age.
It covers heartworm, roundworms and hookworms.
It does not cover fleas, ticks, whipworms or tapeworms.
The label, updated October 2023 · Petipedia: What is Heartgard Plus?
A chew once a month. From 6 weeks of age and 2 pounds.
It covers heartworm, roundworms, hookworms, whipworms and four tapeworms: the flea tapeworm and three that dogs catch by eating rabbits, rodents or livestock.
It does not cover fleas or ticks.
The label, updated July 2026 · Petipedia: What is Interceptor Plus?
A chew once a month, given with food. From 8 weeks of age and 5 pounds.
It covers heartworm, fleas, hookworms, roundworms and whipworms.
It does not cover ticks or tapeworms.
The label warns that serious reactions have been reported when ivermectin was given outside its label together with spinosad, one of the two ingredients.
The label, updated January 2026
Put on the skin once a month. From 6 weeks of age.
It covers heartworm, fleas, ear mites and sarcoptic mange. It covers one tick only, the American dog tick.
In dogs it does not cover intestinal worms.
The label, updated December 2024 · Petipedia: What is Revolution?
Put on the skin once a month. From 7 weeks of age and 3 pounds.
It covers heartworm, fleas, sarcoptic mange, hookworms, roundworms and whipworms.
It does not cover ticks or tapeworms.
The label says not to use it on cats, and to keep dogs from licking the spot for the first 30 minutes.
The label, updated October 2025 · Petipedia: What is Advantage Multi?
These are also approved by the FDA and need a prescription. They replace a monthly dose at home.
An injection every 6 months, from 6 months of age. Only vets and vet technicians who have completed the required training and certification can give it.
It prevents heartworm for 6 months and treats hookworms the dog already has when it is injected.
It does not cover fleas, ticks or other worms.
The label warns that allergic reactions can follow the injection, some of them fatal, and says not to give it to a dog that is sick, underweight or has been losing weight.
The label, revised November 2021 · Petipedia: What is ProHeart?
An injection every 12 months, from 12 months of age. The same training rule applies as for ProHeart 6.
It prevents heartworm for 12 months and treats hookworms the dog already has when it is injected.
It does not cover fleas, ticks or other worms.
The label carries the same warning about allergic reactions, and says not to give it to a dog that is sick, underweight or has been losing weight.
The label, revised November 2021 · Petipedia: What is ProHeart?
An injection every 12 months, or every 8 months where lone star ticks are a risk. From 6 months of age. Approved by the FDA in July 2025.
It covers fleas and the black-legged (deer), American dog, brown dog, Asian longhorned and Gulf Coast ticks for 12 months, and the lone star tick for 8 months.
It does not cover heartworm or intestinal worms, and its label has no Lyme claim.
The label says it may take 3 to 5 days to see a clear drop in ticks, and that allergic reactions, including anaphylaxis, have been reported.
The label, updated August 2026 · Petipedia: What is Bravecto?
These are pesticides registered with the EPA. The FDA's way to tell the two kinds apart: a product registered with the EPA has an EPA registration number on the label, and one approved by the FDA says approved by FDA under a NADA number. None of these three has a heartworm claim.
Put on the skin. From 8 weeks of age. The label says not to reapply within 30 days.
It kills fleas, flea eggs and larvae, ticks including the brown dog, American dog, lone star and deer ticks, and chewing lice. The label says it controls fleas for up to three months and ticks for at least a month, and recommends a monthly dose where ticks are a concern. It also says it aids in the control of sarcoptic mange.
It has no heartworm claim and does not cover intestinal worms.
The label says do not use on cats.
The label, EPA Reg. No. 65331-5
Put on the skin once a month. From 7 weeks of age and 4 pounds.
It repels and kills fleas, ticks including the deer, American dog, brown dog and lone star ticks, and mosquitoes. It also repels biting flies and kills lice.
It has no heartworm prevention claim and does not cover intestinal worms.
The label says do not use on cats, it may be fatal, and to keep cats away from treated dogs for 24 hours.
The label, EPA Reg. No. 11556-143, the large dog size
A collar worn for 8 months. From 7 weeks of age.
It covers fleas, lice and ticks including the black-legged (deer), American dog, brown dog and lone star ticks.
It has no heartworm claim and does not cover intestinal worms.
For a dog that swims once a month or more, the label cuts it to 5 months for fleas and 7 months for ticks. In 2023 the EPA required labels to list the side effects reported to it, with an instruction to take the collar off if they appear. The EPA said the only reported deaths it found probably or definitely related to the collar came from strangulation or injury by the collar itself, often when the release mechanism failed.
The label, EPA Reg. No. 11556-155
Write down each dose and the date in the log on My Pet. The vet sheet prints it, so the vet can see what your dog is on and since when.
What the yearly heartworm test is for, and what a positive result means, is on a page of its own: Does my dog or cat need heartworm protection?
Read 21 September 2026.