Frontline Plus for Dogs and Cats: How It Works and Does It Still Work

By Dr. Zubair Khalid, DVM, MS, PhD · 2026-09-19

Frontline Plus is a topical spot-on flea and tick product that combines two active ingredients, fipronil and (S)-methoprene, in a single tube applied to the skin between the shoulder blades. It is sold over the counter for dogs and cats, kills adult fleas and ticks on contact with the treated coat, and stops flea eggs and larvae from developing into new adults. It remains one of the most widely used flea products in the United States, and it is also one of the most misunderstood. Owners ask two questions more than any other: how does a liquid on the back of the neck kill fleas on the tail, and does Frontline Plus still work after decades on the market.

This guide answers both. It covers the labeled ages and weights for the dog and cat versions, the monthly application technique, what happens when a pet gets wet, exactly which parasites the product targets, and the honest state of the evidence on whether fleas have developed resistance to fipronil. It also explains why the dog product must never be used on a cat, and how fipronil and (S)-methoprene compare with the newer isoxazoline class of flea and tick drugs such as afoxolaner.

This article is educational and is not a substitute for veterinary diagnosis or treatment.

At a Glance

What Frontline Plus Is and What It Contains

Frontline Plus is a fixed-combination topical parasiticide. Each tube contains two active ingredients suspended in a volatile alcohol carrier that spreads across the skin and coat after application.

Fipronil is the adulticide. It belongs to the phenylpyrazole class and is the ingredient responsible for killing fleas and ticks that contact the treated pet. Fipronil was the first of its class approved for veterinary use and remains one of the most studied ectoparasiticides in companion animal medicine.

(S)-methoprene is an insect growth regulator. It is a juvenile hormone analog, which means it mimics a hormone that keeps insects in an immature state. When flea eggs and larvae are exposed to (S)-methoprene, they cannot complete metamorphosis into adults. The result is a break in the flea life cycle rather than an immediate kill of adult insects.

The combination matters. Fipronil alone kills adult fleas, but the flea population in a home is roughly 5 percent adults and 95 percent eggs, larvae, and pupae in the environment. A product that only kills adults leaves a reservoir that reinfests the pet within days. Adding (S)-methoprene attacks that reservoir at the source.

The two ingredients were evaluated together in a controlled study of experimentally infested dogs. Investigators applied fipronil alone, (S)-methoprene alone, or the combination, then measured adult flea kill, egg production, and egg hatch over 12 weeks. The combination delivered both adulticidal activity and inhibition of egg and larval development, which is the pharmacological rationale for the product [2].

How Fipronil and (S)-Methoprene Work

Fipronil disrupts the insect nervous system

Fipronil blocks GABA-gated chloride channels in the insect central nervous system. GABA is the main inhibitory neurotransmitter in insects, and when its channels are blocked, neurons fire without restraint. The insect enters a state of hyperexcitation, loses coordination, and dies. This mechanism is selective for insect GABA receptors over mammalian ones, which is the basis for the wide margin of safety in dogs and cats at labeled doses.

Because fipronil acts on contact rather than by ingestion, a flea does not need to bite the pet to die. It needs only to move through the treated haircoat. This is why flea dirt and live fleas can appear on a treated pet for a short period after application without indicating product failure. The fleas are dying, not feeding.

(S)-Methoprene stops the life cycle

(S)-Methoprene does not kill adult fleas. It works on the immature stages. Adult fleas that feed on a treated pet shed eggs into the environment as normal, but those eggs do not develop into viable larvae, and larvae that contact the ingredient do not pupate into adults. Over several weeks, this depletes the environmental reservoir.

The practical consequence is that owners should not expect the home to be flea-free in 24 hours. Adult fleas already in the environment will continue to emerge and jump onto the pet, where they die. The population declines over one to two months as the reproductive cycle is interrupted. This is why monthly dosing must continue without gaps, even when the pet looks clean.

Speed of kill and duration

In a controlled laboratory study, a single application of fipronil plus (S)-methoprene produced 100 percent flea control on dogs across a six-week challenge period, with no fleas recovered at either 24 or 48 hours after each weekly reinfestation [4]. A separate study of the fipronil, amitraz, and (S)-methoprene combination reported excellent flea knockdown within 24 hours and control of reinfestation for up to seven weeks [1].

Field conditions are less controlled than a laboratory. In a five-month outdoor study comparing three topical products, the fipronil and (S)-methoprene combination maintained greater than 90 percent efficacy against fleas at every time point, though tick efficacy was more variable, ranging from 38.0 to 99.6 percent depending on the tick challenge and time since treatment [3]. That variability is worth understanding. Fleas are the strength of this product. Ticks are a secondary target with real but less consistent performance.

What Frontline Plus Kills and What It Does Not

Fleas

Frontline Plus kills adult fleas and breaks the flea life cycle by preventing eggs from hatching and larvae from developing. In a study of naturally infested dogs, flea efficacy climbed from 38 percent on day 3 to 89.7 percent on day 14, 95.4 percent on day 21, and 100 percent on days 28 and 35 [5]. That trajectory reflects how the product works: it takes several weeks for the environmental reservoir to exhaust itself.

Ticks

The product is labeled for ticks including the brown dog tick (Rhipicephalus sanguineus), the American dog tick (Dermacentor variabilis), the deer tick (Ixodes scapularis), and the lone star tick (Amblyomma americanum). Tick performance varies by species and by how long the tick has been attached. In the same natural infestation study, tick efficacy was 34 percent on day 3, 53 percent on day 7, 62.7 percent on day 14, 65.5 percent on day 21, and roughly 59 percent on days 28 and 35 [5]. That is meaningfully lower than flea efficacy and lower than what owners often assume.

A separate study of fipronil and (S)-methoprene against brown dog ticks found protective 48-hour efficacy fell from 99.6 percent at the start of the treatment period to 43.4 percent by day 35 [6]. The pattern is consistent across studies: tick control is real but short-lived and incomplete compared with flea control.

What it does not cover

Frontline Plus does not treat internal parasites. It has no activity against roundworms, hookworms, whipworms, or tapeworms. It does not prevent heartworm disease. It does not treat sarcoptic mange, demodectic mange, or ear mites as a labeled indication. It does not kill the pupal stage of the flea, which is protected by its cocoon and can survive in the environment for months.

Owners who need heartworm prevention, intestinal deworming, or mange treatment need separate products. This is a common source of confusion because some newer isoxazoline products cover both external and internal parasites in a single chewable.

Labeled Ages and Weights

Dogs

Frontline Plus for dogs is labeled for puppies from 8 weeks of age. The product comes in weight-banded tube sizes, and the correct tube must match the dog's weight. Using a tube sized for a larger dog on a smaller dog is not a substitute for the correct product and increases the risk of an adverse reaction. Using a tube sized for a smaller dog on a larger dog underdoses the animal and reduces efficacy.

Weight bands vary slightly by market and packaging. Owners should read the box and match the dog's current weight to the correct band. A puppy that crosses a weight threshold between monthly doses should be moved to the next band at the next application.

Cats

Frontline Plus for cats is labeled for kittens from 8 weeks of age. Cats use cat-specific tubes only. There is no weight banding for cats in the same way as for dogs because the cat formulation is designed for the full range of adult cat weights.

The rule that matters most

Never apply a dog product to a cat. This is not a dosing nuance. It is a safety rule. Dog formulations of fipronil products may contain permethrin or other pyrethroid ingredients that are toxic to cats, and even fipronil-only dog products are packaged in volumes that can overdose a cat. Permethrin toxicity in cats causes tremors, seizures, hypersalivation, and can be fatal. If a dog product is accidentally applied to a cat, the cat should be seen by a veterinarian immediately.

How to Apply Frontline Plus Correctly

Application technique determines whether the product works. A tube applied to the fur rather than the skin will not distribute properly and may fail entirely.

Step by step

1. Confirm the correct product. Check that the box matches the species and the weight band. Do not use a dog tube on a cat under any circumstances.
2. Part the hair. At the base of the neck, between the shoulder blades, part the coat until you can see skin. This location is chosen because the pet cannot easily lick it off.
3. Place the tube tip against the skin. Not on top of the fur. The tip should touch skin.
4. Squeeze the full contents onto the skin. Empty the entire tube in one spot. Do not split the dose between multiple locations unless the label instructs it.
5. Do not massage it in. Let it absorb. Rubbing it spreads it onto the fur where it does less good.
6. Keep the pet from licking the site. Separate pets in a multi-pet household for several hours after application so one does not groom the product off another.
7. Repeat monthly. Mark the calendar. Gaps of more than a few days reopen the window for flea reproduction.

Common application mistakes

• Applying to the fur instead of the skin
• Using a partial tube to save product
• Bathing the pet immediately before or after application
• Applying to a pet that is wet from swimming or a bath
• Using the wrong weight band
• Skipping a month because the pet looks flea-free

Water Exposure and Bathing

This is one of the most common owner questions, and the answer is more nuanced than most labels suggest.

The fipronil and (S)-methoprene combination is distributed through the sebaceous glands and hair follicles of the skin, which gives it some water resistance after it has fully dried. The product should be allowed to dry completely before the pet is bathed or swims, typically 24 to 48 hours after application.

A controlled study examined what happens when dogs treated with fipronil plus (S)-methoprene are bathed repeatedly. Dogs that were bathed every 48 hours after treatment still had significantly lower tick burdens than untreated dogs from day 2 to day 28, and treated dogs that were not bathed had lower flea burdens than untreated dogs from day 1 through day 56 [7]. The study confirms that bathing does not eliminate efficacy, but it also shows that the treated-and-bathed group did not perform identically to the treated-and-not-bathed group.

The practical guidance: wait at least 48 hours after application before bathing or swimming, use a gentle shampoo rather than a harsh degreasing or medicated shampoo, and do not bathe more often than necessary during the treatment month. Frequent bathing with strong shampoos will strip the product from the coat faster than the label month.

A separate study compared monthly fipronil plus (S)-methoprene against weekly hygiene shampooing in a simulated flea-infested environment. The shampoo group did not control fleas adequately, which reinforces that bathing is not a substitute for an insecticidal product [8].

Side Effects and What to Do About Them

Frontline Plus has a long safety record at labeled doses in dogs and cats from 8 weeks of age. Adverse reactions are uncommon and usually mild.

Reported reactions

• Temporary irritation, redness, or itching at the application site
• Transient greasy or matted appearance of the fur at the application site
• Drooling or hypersalivation if the pet licks the application site before it dries
• Mild lethargy or reduced appetite in the first 24 hours after application

When to call a veterinarian

• Persistent vomiting or diarrhea
• Tremors, twitching, or unsteady gait
• Difficulty breathing or facial swelling
• Severe or spreading skin reaction
• Any reaction in a pet with a known sensitivity to fipronil or (S)-methoprene

Most application-site reactions resolve without treatment. If a pet licks the site and drools, offer water and monitor. If neurological signs appear, seek veterinary care the same day.

Rabbits and small mammals

Fipronil is toxic to rabbits. This is a well-documented and serious concern. Rabbits that receive fipronil, even at doses that would be appropriate for a dog or cat, can develop severe neurological signs and die. Frontline Plus and any other fipronil-containing product must never be used on rabbits. The same caution applies to other small mammals where fipronil has not been evaluated or is known to be unsafe. Owners of rabbits, guinea pigs, hamsters, and similar pets should not assume that a product safe for a dog or cat is safe for their species.

Does Frontline Still Work? The Resistance Question

This is the question owners ask most often, and it deserves a direct answer rather than a marketing claim in either direction.

The evidence that the product still works

Fipronil remains highly effective against fleas in controlled laboratory studies. In a 2020 in vitro study using the larval packet test, fipronil caused 99 percent or greater mortality of brown dog ticks at low, recommended, and high concentrations [9]. In the 2011 comparative study, fipronil plus (S)-methoprene produced 100 percent flea control across six weeks of weekly reinfestation, while the comparator oral product lost efficacy over the same period [4]. In the 2015 outdoor study, the fipronil and (S)-methoprene combination maintained greater than 90 percent flea efficacy at every time point across five months of monthly treatment [3].

These are not trivial results. A product that has lost efficacy would not produce 100 percent flea control in a controlled challenge study.

The evidence behind owner reports of failure

Owners who say Frontline Plus stopped working are usually describing a real phenomenon, but the cause is often not resistance.

Application failure. The most common reason a topical flea product fails is that it was not applied correctly. Product applied to the fur instead of the skin, a partial dose, a missed month, or bathing too soon after application all reduce efficacy. The bathing study showed that even when the product is applied correctly, frequent bathing reduces performance compared with no bathing [7].

Reinfestation pressure. A pet in a heavily infested environment, a home with a large flea reservoir, a yard shared with untreated animals, or a multi-pet household where only one pet is treated will continue to see fleas. The product is working, but the challenge is overwhelming the monthly dose. This is not resistance. It is an environmental load problem.

Life cycle timing. Owners who expect the pet to be flea-free within days are measuring the wrong endpoint. The natural infestation study showed flea efficacy climbing from 38 percent on day 3 to 100 percent on day 28 [5]. A pet that still has fleas two weeks into treatment may be on a normal trajectory.

Short tick duration. Tick efficacy declines faster than flea efficacy. The brown dog tick study showed 48-hour tick efficacy falling from 99.6 percent to 43.4 percent over 35 days [6]. Owners who rely on the product for tick control may perceive failure when the issue is the labeled duration for ticks being shorter than the flea duration.

Genuine reduced susceptibility. True resistance to fipronil in flea populations has been reported in some regions, and reduced susceptibility is a plausible contributor in areas with heavy, repeated fipronil use. The evidence base for confirmed field resistance in the United States is less robust than owner anecdotes suggest. The honest position is that resistance is possible, application failure and reinfestation pressure are more common, and a veterinarian can help distinguish the two.

How to tell the difference

If a pet on monthly Frontline Plus still has fleas, the first step is to verify application technique and confirm no doses were missed. The second step is to assess the environment: are other pets treated, is the yard or home heavily infested, has the pet been bathed frequently. If technique and environment are correct and fleas persist, switching to a different drug class is reasonable. A veterinarian can help make that decision.

Frontline Plus vs NexGard and the Isoxazolines

The isoxazoline class includes afoxolaner (NexGard), fluralaner (Bravecto), sarolaner (Simparica), and lotilaner (Credelio). These are oral or topical products that work by blocking insect and acarine GABA-gated chloride channels through a different binding site than fipronil. They are systemic, meaning the drug is absorbed into the bloodstream and the parasite is exposed when it takes a blood meal.

The key differences matter for owners choosing between products.

Speed of kill

Isoxazolines kill fleas and ticks faster than fipronil-based topicals in head-to-head comparisons. A study comparing a topical fipronil and permethrin combination against oral afoxolaner found that the topical product produced significantly greater flea efficacy at 30 minutes after infestation on day 7 (70 percent versus 8 percent) and on day 28 (34 percent versus 18 percent) [10]. That early kill speed matters for pets with flea allergy dermatitis, because a flea that dies before it bites causes less allergic reaction.

Spectrum

Isoxazolines are labeled for fleas and ticks, and some are labeled for additional parasites. Frontline Plus is labeled for fleas and ticks only. Owners who need heartworm prevention or intestinal deworming need a separate product with Frontline Plus but may get broader coverage from a combination isoxazoline product.

Route of administration

Frontline Plus is topical. Isoxazolines are available as oral chews or topical spot-ons. Some pets refuse oral medication, and some owners prefer to avoid systemic drugs. Others find topical application messy or difficult on long-haired pets. Route of administration is a legitimate factor in product choice.

Onset and duration

Fipronil-based topicals work on contact and begin killing fleas within hours of application. Isoxazolines require the flea to bite the pet to be exposed, which means a flea can feed and cause an allergic reaction before it dies. The trade-off is that isoxazolines often last longer per dose and kill faster once the parasite is exposed.

Resistance considerations

Because isoxazolines act at a different binding site than fipronil, a flea population with reduced susceptibility to fipronil is not automatically cross-resistant to isoxazolines. This is one reason veterinarians may switch a pet from a fipronil product to an isoxazoline when flea control appears to be failing. It is also why rotating drug classes is sometimes recommended in high-pressure environments.

Which is right for your pet

There is no universal answer. A pet with flea allergy dermatitis may benefit from the faster kill of an isoxazoline. A pet with a known sensitivity to oral medication may do better on a topical. A pet in a low-pressure environment with good owner compliance may do perfectly well on Frontline Plus for years. The decision should be made with a veterinarian who knows the pet's history, the local parasite pressure, and the owner's ability to comply with monthly dosing.

Frontline Plus vs Other Fipronil Products

Frontline Plus is not the only fipronil product on the market. Several formulations combine fipronil with different partner ingredients for different purposes.

Fipronil plus amitraz plus (S)-methoprene was developed to enhance tick efficacy. In a controlled study, this combination provided excellent flea knockdown within 24 hours and controlled reinfestation for up to seven weeks [1]. The addition of amitraz broadens tick coverage.

Fipronil plus (S)-methoprene plus cyphenothrin is labeled for dogs and was evaluated against the deer tick. A single dose prevented establishment of new infestations and repeated weekly reinfestations for four weeks, with 93 to 99 percent efficacy at 6-hour assessments and 98 to 100 percent at 24-hour assessments [11]. This product is for dogs only.

Fipronil plus permethrin combinations are widely used in dogs outside the United States and provide repellency against ticks in addition to killing them. Studies of these combinations show repellency against Ixodes ricinus ranging from 72.6 to 96.3 percent at 4 hours, and 100 percent at 24 hours after exposure on days 2, 7, and 14 [12]. These products are not safe for cats because of the permethrin.

The common thread is that fipronil is a versatile base molecule that can be paired with different partner ingredients to shift the spectrum toward ticks, add repellency, or extend duration. Frontline Plus sits at the flea-control end of that spectrum, with solid flea efficacy and moderate tick efficacy.

Special Populations and Precautions

Puppies and kittens

Frontline Plus is labeled for puppies and kittens from 8 weeks of age. Younger animals should not receive the product. Owners of very young puppies or kittens with flea infestations should consult a veterinarian about safe options.

Pregnant and nursing animals

Fipronil and (S)-methoprene have been used in pregnant and lactating dogs and cats under veterinary supervision. Owners should confirm with their veterinarian before applying the product to a pregnant or nursing pet.

Sick, debilitated, or underweight animals

The label advises against use on sick, debilitated, or underweight animals. A pet that is unwell may have altered skin barrier function or reduced ability to metabolize the drug. A veterinarian should evaluate the pet before a flea product is applied.

Multi-pet households

Separate treated pets from untreated pets for several hours after application so the product is not groomed off. This is especially important in households with cats and dogs, where a cat grooming a treated dog could be exposed to a dog-only ingredient.

Pets with known drug sensitivities

A pet with a prior reaction to fipronil or (S)-methoprene should not receive the product again. A veterinarian can recommend an alternative class.

Questions to Ask Your Veterinarian

• Is Frontline Plus the right product for my pet's flea and tick risk?
• My pet still has fleas on monthly Frontline Plus. Is this application failure, reinfestation pressure, or reduced susceptibility?
• Should I switch to an isoxazoline product given my pet's history?
• Does my pet need additional coverage for heartworm or intestinal parasites?
• How should I handle flea control in a multi-pet household?
• My pet has flea allergy dermatitis. Does speed of kill matter for my pet?
• Is it safe to use Frontline Plus on my pet given its age, weight, and health status?
• How should I manage the home environment to reduce reinfestation?

Limitations and When to Contact a Veterinarian

This article describes the labeled use and published evidence for Frontline Plus. It cannot account for your pet's individual health status, prior reactions, concurrent medications, or the specific parasite pressure in your area. Those factors require a veterinarian who can examine the pet and review the full history.

Contact a veterinarian promptly if any of the following occur:

• Your pet develops tremors, twitching, unsteady gait, difficulty breathing, or facial swelling after application
• Your pet has persistent vomiting, diarrhea, or lethargy beyond 24 hours after application
• A dog product was accidentally applied to a cat
• A fipronil product was accidentally applied to a rabbit or other small mammal
• Your pet has a severe or spreading skin reaction at the application site
• Fleas or ticks persist despite correct monthly application for two or more consecutive months
• Your pet has flea allergy dermatitis and continues to scratch despite treatment
• Your pet is pregnant, nursing, under 8 weeks of age, or has a chronic illness and you are unsure whether the product is appropriate

For a suspected poisoning or adverse reaction, contact your veterinarian or a pet poison control service immediately. Do not wait to see if signs resolve on their own.

Frequently Asked Questions

How long does Frontline Plus take to work?

Frontline Plus starts killing fleas within hours of application, and controlled studies show complete flea control within 24 hours of infestation on treated dogs [1][4]. Full resolution of a home infestation takes longer because the product must also break the flea life cycle in the environment, which typically takes one to two months of consistent monthly use.

Does Frontline Plus still work, or have fleas become resistant?

Fipronil remains highly effective in controlled studies, with 100 percent flea control reported across six weeks of weekly reinfestation in one trial [4] and greater than 90 percent flea efficacy across five months in another [3]. Most owner reports of failure trace to application error, missed doses, bathing too soon, or overwhelming reinfestation pressure rather than confirmed resistance. Reduced susceptibility is possible in some regions, and a veterinarian can help determine whether a product switch is warranted.

Can I use Frontline Plus for dogs on my cat?

No. Dog formulations may contain ingredients toxic to cats, and the tube volumes are not sized for cats. Cats must receive the cat-specific product. If a dog product is accidentally applied to a cat, contact a veterinarian immediately.

Is Frontline Plus safe for rabbits?

No. Fipronil is toxic to rabbits and can cause severe neurological signs and death. Frontline Plus and all other fipronil-containing products must never be used on rabbits or other small mammals.

How soon can I bathe my dog after applying Frontline Plus?

Wait at least 48 hours after application before bathing or letting the pet swim. A controlled study showed that dogs bathed every 48 hours after treatment still had significantly lower tick burdens than untreated dogs, but the treated-and-bathed group did not perform identically to the treated-and-not-bathed group [7]. Frequent bathing with strong shampoos will reduce efficacy.

What is the difference between Frontline Plus and NexGard?

Frontline Plus is a topical product containing fipronil and (S)-methoprene that kills fleas and ticks on contact. NexGard contains afoxolaner, an oral isoxazoline that kills fleas and ticks after they bite the pet. Isoxazolines generally kill faster once the parasite is exposed, but they require a bite, which matters for pets with flea allergy dermatitis [10]. The choice depends on the pet's risk profile, the owner's preference for topical versus oral administration, and whether broader parasite coverage is needed.

Can I use Frontline Plus on a puppy or kitten?

Frontline Plus is labeled for puppies and kittens from 8 weeks of age. Younger animals should not receive the product. A veterinarian should be consulted for flea control in animals under 8 weeks.

What should I do if my pet still has fleas after using Frontline Plus?

First verify that the product was applied correctly to the skin, that no monthly doses were missed, and that the pet has not been bathed too soon after application. Then assess the environment, including other pets and the home. If fleas persist despite correct use for two or more consecutive months, consult a veterinarian about switching to a different drug class.

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Sources

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2. Efficacy of fipronil/(S)-methoprene combination spot-on for dogs against shed eggs, emerging and existing adult cat fleas (Ctenocephalides felis, Bouché).
3. Five-month comparative efficacy evaluation of three ectoparasiticides against adult cat fleas (Ctenocephalides felis), flea egg hatch and emergence, and adult brown dog ticks (Rhipicephalus sanguineus sensu lato) on dogs housed outdoors.
4. Comparative efficacy on dogs of a single topical treatment with the pioneer fipronil/(S)-methoprene and an oral treatment with spinosad against Ctenocephalides felis.
5. Efficacy of a Novel Topical Combination of Fipronil 9.8% and (S)-Methoprene 8.8% against Ticks and Fleas in Naturally Infested Dogs.
6. Efficacy of slow-release collar formulations of imidacloprid/flumethrin and deltamethrin and of spot-on formulations of fipronil/(s)-- methoprene, dinotefuran/pyriproxyfen/permethrin and (s) -methoprene/amitraz/fipronil against Rhipicephalus sanguineus and Ctenocephalides felis felis on dogs.
7. Does bathing affect tick and flea burdens and ectoparasiticide effectiveness of a spot-on formulation (fipronil + (S)-methoprene) for dogs?
8. Comparative efficacy on dogs of a single topical treatment with fipronil/(S)-methoprene or weekly physiological hygiene shampoos against Ctenocephalides felis in a simulated flea-infested environment.
9. A comparison of the efficacy of two commercial acaricides (fipronil and amitraz) with Azadirachta indica (neem) on the brown dog tick (Rhipicephalus sanguineus) from canines in Trinidad.
10. The sustained speed of kill of ticks (Rhipicephalus sanguineus) and fleas (Ctenocephalides felis felis) on dogs by a spot-on combination of fipronil and permethrin (Effitix(®)) compared with oral afoxolaner (NexGard(®)).
11. Efficacy of a proprietary formulation of fipronil/(S)-methoprene/cyphenothrin against Ixodes scapularis tick infestations on dogs.
12. Repellency and acaricidal efficacy of a new combination of fipronil and permethrin against Ixodes ricinus and Rhipicephalus sanguineus ticks on dogs.