Activyl for Dogs and Activyl for Cats FAQs

These FAQs should answer most of your questions, but if there is something more you want to know you can always contact us for more information.

Q. Should I bathe my pet before treatment?

A. Bathing your pet is not required. According to veterinary industry standards, your pet should not be allowed to swim or be shampooed within 24 hours after applying a spot-on product.

Q. Can Activyl for Dogs and Activyl for Cats be used on pets with itchy skin?

A. Activyl can be used in the management of pets with itchy skin due to flea bites—also known as flea allergy dermatitis or FAD.1,2.

Q. Can I use Activyl for Dogs and Activyl for Cats all year-round?

A. Fleas can be a year-round problem indoors and outdoors. Applying Activyl every four weeks ensures your dog and cat will be protected from fleas throughout the year.

Q. How does Activyl for Dogs and Activyl for Cats spread over my pet's body?

A. Activyl spreads in the lipid layer of your pet's skin.

Q. Should Activyl for Dogs and Activyl for Cats be used differently on long- and short-haired pets?

A. Activyl spreads throughout the skin and coat of your dog or your cat the same way in both long- and short-haired breeds. To provide the best care for your pet, just ensure that you select the correct size of Activyl for your dog or cat based on its weight and apply the product directly to the skin, not on top of the coat.

Q. Do fleas need to bite for Activyl for Dogs and Activyl for Cats to work?

A. Activyl remains on the surface of your pet. Fleas get exposed to Activyl when they jump onto a treated animal. It can enter the flea either by moving through their outer surface (called a cuticle) or if the flea happens to ingest some. Since Activyl is on the surface of the pet and not in the pet's bloodstream, fleas do not need to take a blood meal for Activyl to start working.

Q. Why do I see more fleas after I have applied Activyl for Dogs and Activyl for Cats or other spot-on products?

A. Fleas tend to hide away unless disturbed. When Activyl starts to work, fleas lose coordination and will sometime move to the coat's surface. This may make them easier to see. Please don't worry; these fleas will die soon.

Q. Why can I still see fleas after I have treated my pet with Activyl for Dogs and Activyl for Cats or other spot-on products?

A. The fleas you see on your pet are fleas that have newly jumped from the environment on your pet. Those fleas will die soon. It is important to take a three-pronged approach to treating fleas. This is because only a small percentage of the flea population is on your pet. Most of the flea population exists as immature stages (eggs, larvae and pupae) in your pet's surroundings. Activyl is active against both adult fleas on your pet as well as immature fleas in your pet's environment,1,3 but it takes some time to clean out the flea population in the house. To help speed this process up, you should clean your house thoroughly (for example, by washing your pet's bedding and thorough vacuuming your pet's favorite spots in the house) to help reduce the number of immature fleas present.

If there is a serious infestation, it may take some time to control. But any fleas you see on your pet a few days to weeks after treatment probably represent re-infestation from fleas emerging from cocoons in the environment. Activyl lasts for 4 weeks 1,4 and it is important to repeat treatment on time every month. At least 3 consecutive treatments are recommended for effective control of flea infestations on the pet and in the pet's environment, and continued treatment is needed to prevent your pet from bringing new fleas home.

Q. Can my pet swim or be washed after I apply Activyl for Dogs and Activyl for Cats?

A. Activyl has been tested to make sure it is not easily rinsed or washed off.1,5 However, Activyl must first be allowed to spread and dry on the skin. According to veterinary industry standards, you should not wash your pet or allow it to swim for 24 to 48 hours after application. Consult the product label4 and your veterinarian for more information.

Q. Can I use Activyl for Dogs and Activyl for Cats when my pet is on medication?

A. You should consult the product label4 and your veterinarian before applying any product if your pet is on medication.

Q. Can I apply two different spot-on products?

A. Spot-on products are available for fleas and also for other parasites. Please consult your veterinarian for the most appropriate treatment for your pet.

Q. Can I use Activyl on pets other than dogs and cats?

A. Activyl for Dogs is designed for use on dogs and Activyl for Cats is designed for use on cats. Please consult the product label and your veterinarian for advice on suitable treatment for other pets.

Q. How frequently should Activyl for Dogs and Activyl for Cats be applied?

A. One treatment of Activyl lasts for 4 weeks and it is important to repeat treatment on time.1,4 Year-round treatment is recommended for optimal treatment and control. Please consult the product label4 and your veterinarian for further information.

Q. When should I start treating my pet for fleas?

A. Activyl for Dogs, Activyl for Cats and Activyl Tick Plus for Dogs only can be administered as early as 8 weeks of age.1,4 Dogs should weigh at least 4 lbs and cats should weigh at least 2 lbs.1,4 There are very few places in the world where there are no fleas. In warmer climates, fleas are present all year round, while in more temperate climates, fleas are present mainly from late spring through to late fall and even longer, thanks to central heating. To be on the safe side, Activyl should be applied all year-round to avoid giving flea populations a chance to build up on your pet and in your home.

Consult your veterinarian about using Activyl on your pet and when to apply it.

Q. How does Activyl for Dogs and Activyl for Cats work?

A. Indoxacarb, the active ingredient in Activyl, becomes fully insecticidally active after contact with flea enzymes. This is what makes Activyl unique. Read more about how Activyl works.

Q. Does Activyl for Dogs and Activyl for Cats kill fleas before they can lay eggs?1,4,6

A. Fast-acting flea products like Activyl may paralyze and kill fleas before they can lay eggs.

  • 1. Data on file, Merck Animal Health.
  • 2. Fisara P, Sargent R, Flochlay-Sigognault A, Frenais R, Guerino F. Efficacy of indoxacarb spot-on in resolving clinical signs of flea allergy dermatitis in dogs cats and other field conditions. Presented at the BSAVA/WSAVA/FECAVA World Congress, 12-15 April, 2012, Birmingham, UK.
  • 3. Guerino F, Qureshi T, Hair J., Young D, Fiourie J. Indoxacarb Kills Developing Stages of Fleas in the Environment of Treated Cats. Presented at the WSAVA/FECAVA/BSAVA World Congress. 12-15 April 2012. Birmingham, UK.
  • 4. Activyl® Product Insert
  • 5. Qureshi T, Balgburn B, Yound D, Sun F, Guerino F. Effects of water immersion and shampooing on the efficacy of an indoxacarb spot-on against cat flea (Ctenocephalides felis) infestation on dogs. Presented at the BSAVA/WSAVA/FECAVA World Congress, 12-15 April 2012, Birmingham, UK.
  • 6. Dryden MW, Payne PA, Smith V, Heaney K, Sun F. Efficacy of indoxacarb applied to cats against the adult cat flea, Ctenocephalides felis, flea eggs and adult flea emergence. Parasite Vectors. 2013; 6:126.

Activyl Tick Plus for Dogs Only FAQs1

These FAQs should answer most of your questions, but if there is something more you want to know, you can always contact us for more information.

Q. Aren't ticks active just in summer?

A. No. The tick season extends well into fall—even more so with unusually warmer weather—and some tick species are remarkably hardy in winter, particularly if the temperature is above 45°F (or 7°C).

Q. We have a cat, too. Can I still use Activyl Tick Plus on my dog?

A. Activyl Tick Plus must never be used on cats. One of the active ingredients (permethrin) in Activyl Tick Plus is toxic to cats, so we recommend keeping dogs and cats separated for 24 hours.

Q. Ticks are only found out in the country, right?

A. No, they can be found much closer to home. This is because all sorts of mammals (deer, raccoons, rabbits, squirrels, etc.) can carry ticks into suburbs, parks, and gardens, where the ticks fall off and lay their eggs. One tick species, the brown dog tick, can live indoors all year round. Learn more about ticks.

Q. How do ticks get on my dog?

A. Ticks are smart hunters. Called "questing," they congregate in vegetation and grasses—even in tree boughs—waiting for a warm-blooded host to brush by. They are attracted to warmth and motion, and it is speculated that ticks can even recognize shadows! Although they can't jump, they transfer easily and will crawl long distances to reach a host (your pet sitting in the grass, for example).

Q. How do I know if there's a tick on my dog?

A. If there's a tick on your dog, it will have burrowed down closer to the skin. After every excursion you need to take the time to carefully look through your pet's coat from head to tail, parting the hair as you go. Be sure to check around your pet's ears, in the "armpits" and between the toes. Learn how to check your dog for ticks.

Q. What should I do if I find a tick on my dog?

A. If the tick has not attached, it can easily be brushed off and disposed of. If it has attached, or is engorged, it must be removed carefully so as not to leave the mouthparts in your pet's skin, which could cause infection. Learn how to remove a tick from your dog.

Q. What are the symptoms of Lyme disease?

A. Your dog will usually have a fever, and rarely, a rash circling the bite area. Different tick-borne diseases have different symptoms: lethargy, temporary paralysis, weakness, etc., so if you see any unusual signs in your dog, contact your veterinarian. Early stages are fully treatable, but if left untreated, can develop into a more serious form of disease months later.

Q. If my dog gets a disease from a tick, is it contagious?

A. Tick-borne diseases cannot be transmitted from dog to human—however, if you have ticks in your area, both you and your dog may be bitten by them and therefore vulnerable to some of the same diseases. You should be just as diligent checking yourself and your family for ticks!

Q. Can ticks infest your house, like fleas?

A. Absolutely, yes. One type of tick, the brown dog tick, can infest a home as easily as fleas. But unlike fleas (which lay eggs residing on the dog that then roll off the dog into carpets, sofas and bedding), ticks lay eggs in cracks and crevasses like floors and baseboards.

Q. What can I do if I know there are ticks outside my house?

A. To begin with, ticks don't like a neat garden! They like moist, damp areas of tall vegetation, so when you keep your grass mowed and plants trimmed, the environment becomes less than ideal for their development. If you find many ticks, you can use pesticides—but make sure they are safe for your pets and environmentally friendly.


1. Blagburn BL, Dryden MW. Biology, treatment, and control of flea and tick infestations. Vet Clin N Am Small Anim. 2009;39(6):1173-1200.

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