Flea Control and Flea Prevention In Dogs and Cats


We’ve had about enough of them, haven’t we?

And your pets have, too!

The dog I saw today absolutely covered in fleas inspired me to write today’s post on flea control.


Simply because there are so many good flea control products available there is absolutely no excuse for your pet to have fleas! Let’s look at some products:

Click here for an updated post on flea control products (posted 5-12-2017).  For example, Frontline Plus is now a very old molecule, and many fleas are resistant to it. Frontline Spray is still effective, but tedious, as it has to be applied at least weekly. Capstar has given way to Simparica, Comfortis and Bravecto. Revolution is still dynamite, as is Mycodex Environmental Spray. And, both yard treatment granules still do a great job.

Frontline Plus:  I’m a huge fan of Frontline Plus because it is extremely effective, very safe and easy to use. It gives both flea control and flea prevention for both dogs and cats. Flea control means it kills adult fleas; flea prevention means it kills the eggs and larvae, preventing them from becoming adult fleas. An ingredient called an Insect Growth Regulator (IGR) kills the eggs and larvae.  It is applied monthly, starting at the base of the spine, making a stripe up the back toward the head. Part the hair as you go so that you can apply it to the skin. It’s OK that some gets on the hair. From where you apply it Frontline Plus covers the body in about two days by traveling through the oil layers of the skin and hair, propelled by body heat and body motion. While up to two baths per month are allowed without having to repeat Frontline Plus, we recommend the fewest baths possible to maximize its effectiveness.

Frontline Spray:  Frontline Spray is fantastic for those situations where we need a really quick kill of adult fleas with a full month of residual effect. While it doesn’t give flea prevention, it is also excellent for clients who have several very small dogs. Small dogs (and cats!) can be treated easily and economically and with the same safety levels as Frontline Plus.

Capstar:  When our Novartis Animal Health representative first visited me with information about Capstar and told me it would begin to kill adult fleas within twenty minutes and go on killing fleas for 24 hours, I was skeptical. I didn’t give it much thought again until one very busy afternoon a client brought in a little kitten covered with fleas. She was so black with them that you literally couldn’t put your finger anywhere on her without touching ten fleas. I gave her a Capstar tablet and put her back in her carrier. She waited in the lobby until I could work her in to our very full afternoon schedule. About thirty minutes later I opened her carrier to find the bottom of it covered in fleas. Dead fleas. I was a believer. We use Capstar several ways in our practice now:

  • for near-immediate kill of adult fleas where there is a heavy infestation, while simultaneously administering monthly flea control and prevention.
  • It is also excellent for administration to a boarder who arrives flea-infested, before admitting him to our boarding facility.
  • for ongoing adult flea control in combination with Sentinel heartworm preventive, which includes a flea preventing ingredient. See below for more on Sentinel. The schedule is as follows: One Capstar now, then one weekly for four weeks, then monthly. The cost, safety and effectiveness are comparable to other forms of flea control and prevention.

Comfortis:   Comfortis is really making waves in veterinary flea control products. It is an oral medication in tablet form. Comfortis begins killing adult fleas within 30 minutes and lasts for a month. There is but one troubling side effect, and that is vomiting in some dogs. Most dogs, however, who take Comfortis with or just after a meal do not vomit.  Comfortis is made by the well-known Eli Lilly Pharmaceutical Company (Editor’s Note:  Elanco is a division of Eli Lilly and Company). Comfortis has also been approved for use in cats, although the dosage rate is different from dog dosing.

Revolution:  Revolution is the number one heartworm preventive for dogs and cats in our practice. We limit it to use in dogs with no intestinal parasites because it is not labeled for prevention of hookworms or roundworms, both of which can infect people, nor is it labeled for prevention of whipworms (which, generally, are not considered a danger to people). Revolution heartworm preventive has the ability to both control and prevent fleas with a single ingredient and monthly application. After application do not touch your pet in the area the medication is applied for two hours and don’t bathe him for 24 hours.

Sentinel:  Sentinel is an oral heartworm preventive for both dogs and cats in a chewable tablet which also contains a second, flea preventive, ingredient that causes any adult fleas that bite your pet to lay eggs that are defective. Thus, those eggs will never be able to mature into adult fleas and bite your pet. However, you must note that Sentinel has no other effect on adult fleas, so any fleas in your home or environment will live a normal lifespan, usually a few months. If adult fleas are a problem you will need a flea adulticide such as Capstar, Frontline Spray or Frontline Plus. However, if your pet lives a very confined, isolated existence Sentinel alone may suffice as your total flea program. See above for instructions on using Capstar in combination with Sentinel.

No matter what flea control and flea prevention you use on your pet, remember this: It can kill only the fleas that are on your pet! It can’t kill the ones that are in the couch, carpet, pet bed and yard! So, if you are seeing fleas on your pet in the face of proper administration and maintenance of one of the products listed above, you will need to address the fleas in the environment.


Mycodex Environmental Spray:   Mycodex Environmental Spray has been a mainstay in our practice for years. It’s easy to use, extremely effective and shows no evidence of reduced effectiveness or resistance despite years of use. It kills adult fleas, eggs and larvae. Eggs and larvae are killed with its Insect Growth Regulator (IGR) ingredient.  Please note that Mycodex Environmental Spray is a directional spray, not a fogger. Foggers are a waste of your time and money, despite what TV would have you believe. Use Mycodex Spray on your fabric furniture (test an inconspicuous area first), carpets and rugs. Treat every room in the house, even if there are areas the pets are not allowed to enter. Repeat treatment in three weeks when the pupa stage hatches out. If your infestation is severe, repeat treatment monthly for three months, then every three months year-round (readers in cold climates may be able to treat less often). If your infestation is mild, simply treat every three months after the initial two treatments.


If you need quick kill of adult fleas in the yard, use a product with a permethrin or pyrethrin active ingredient in a spray form. Keep pets off of the yard until the spray is dry.

Granular products, while not the fastest flea killers, have the longest duration in the yard. Any of the following products will last two to three months, properly applied.

If you still can’t solve your environmental flea control problems, you probably need the help of a registered pest control company.  You can find them in the Yellow Pages.

See you tomorrow, Dr. Randolph.

No comments yet

  1. Are you SERIOUSLY recommending using a permethrin product in a yard?!?!?! And you make this recommendation without any comment whatsoever about the danger to cats?

  2. I have a friend that brought their dog over and gave our puppies fleas… They were only three months almost four months old and my friends dog had fleas. My new pups had never been exposed to fleas and now there seems to be a non step reproduction of the fleas. We give them flea baths, used flea bombs, and collars and the fleas just keep coming back n no matter what. I have found that my sister is very allergic to the bites herself and can’t stay with us when she’s home from college! I’m not sure how we can effectively remove them from the house- beds, clothes, closets, pets, etc. We really need to get ride of the fleas! My friend had used flea bombs and it worked for them but they also have a smaller house with less carpet and bedding than me and my family. What should/ can I do?? I need help and would love more information!!!! Thank you 🙂

    • First, don’t waste your time or money on bombs. Click here to read why. Next, read this article and notice under the heading “IN THE HOUSE” there is a schedule to follow for treating the house. Please follow it and don’t cut corners. Lastly, scroll down to “IN THE YARD” and notice the two granular products listed; you can purchase either one to create a flea-free zone all the way around your house. Any fleas trying to enter will have to come in contact with poisonous granules, and will be killed. Keep up with monthly, year-round heartworm preventive and be sure you get one with flea prevention. Thanks for reading MyPetsDoctor.com.

  3. Will Mycodex work in non-carpeted areas as well?
    I have a huge problem with fleas in the basement which has a laminate floor.

    • Yes, Kelly, Mycodex home treatment works great on all surfaces. In rooms where there are no carpets we recommend misting about one foot up the wall and about one foot out from the baseboard. Fleas can be harbored in tiny cracks too small to see!

  4. Thank you so much for the informative article on flea control because I was looking for a solution for my cat for so long. Actually she has acquired a lot of fleas lately and I was quite worried about getting rid of them. Thank you for the information.

  5. I have been trying to find information – none is on the can for the Mycodex Plus Environmental Spray. A rough idea of the drying time and do we need to leave the home after spraying and for how long? Thank you.

    • I’m pretty sure the label says be out of the house for 4 hours. However, it has been my experience that the longer you’re gone the greater the effectiveness, so leaving the house closed up all day while you’re gone to work is terrific, if that can work for you. Of course, all pets have to be out of the house, including birds (maybe even especially birds) and cover your aquarium if you have one.

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