The Ultimate Guide to Fleas on Dogs and Cats

Fleas are a common problem for both dogs and cats, and they can be really difficult to get rid of. In this article, we’ll discuss the different types of fleas and how to treat them properly. We’ll also give you tips on how to prevent Fleas from establishing themselves in the first place. Finally, we’ll provide you with a list of ways to get rid of fleas on dogs or cats if they’re already infested. So whether you’re a pet owner, a veterinarian, or just someone who wants to know more about Fleas, read on!

Fleas on dogs and cats!  These small dark brown insects prefer temperatures of 65-80 degrees and humidity levels of 75-85%… so for some areas of the country they are more than just a “summer” problem.  Dogs and cats often get infested with fleas through contact with other animals or contact with fleas in the environment. The strong back legs of this insect enable it to jump from host to host or from the environment onto the host.  (Fleas do not have wings so cannot fly!)  The flea’s bite can cause itching for the host but for a sensitive or flea-allergic animal, this itching can be quite severe and leads to hair-loss, inflammation and secondary skin infections.  Some pets, hypersensitive to the flea’s saliva, will itch all over from the bite of even a single flea!  The flea information presented here will focus on treatment for and prevention of fleas, which, let’s face it, is just as important to the pet as it is to the pet’s caretakers!

Fleas On Dogs and Cats

How do you know if fleas are causing all that itching (called pruritus)?  Generally, unlike the burrowing, microscopic Demodex or Scabies Mites, fleas can be seen scurrying along the surface of the skin.  Dark copper colored and about the size of the head of a pin, fleas dislike light so looking for them within furry areas and on the pet’s belly and inner thighs will provide your best chances of spotting them.  Look for “flea dirt”, too.  “Flea dirt” looks like dark specks of pepper scattered on the skin surface. See the image of flea dirt near the bottom-right of this article. If you see flea dirt, which is actually flea feces and is composed of digested blood, pick some off the pet and place on a wet paper towel.  If after a few minutes the tiny specks spread out like a small blood stain… it’s definitely flea dirt and your pet has fleas!  Flea dirt may be your only evidence of a flea infestation but believe the evidence!  If there is flea dirt there are surely fleas present.  You need to begin your war on the pests.

  Understanding The Flea Life Cycle

In order to understand how and why treatment options work, we must first understand the flea’s life cycle since the various modern treatment and prevention products work on different parts of this life cycle.  There are several stages to its life cycle:  egg, larva or caterpillar, pupa or cocoon, and adult.  The length of time it takes to complete this cycle varies depending upon the environmental conditions such as temperature, humidity, and the availability of a nourishing host.   Yes… the various flea stages are quite resistant to freezing temperatures.  The flea’s host is a  warm-blooded animal such as a dog or cat (or even humans!)  The adult female flea typically lives for several weeks on the pet.   During this time period she will suck the animal’s blood two to three times and lay twenty to thirty eggs each day.  She may lay several hundred eggs over her life span.  These eggs fall off of the pet into the yard, bedding, carpet, and wherever else the animal spends time.  

These eggs then proceed to develop where they have landed.  Since they are about 1/12 the size of the adult, they can even develop in small cracks in the floor and between crevices in carpeting.  The egg then hatches into larvae.  These tiny worm-like larvae live among the carpet fibers, in cracks of the floor, and outside in the environment.  They feed on organic matter, skin scales, and even the blood-rich adult flea feces. The larvae grow, molt twice and then form a cocoon and pupate, waiting for the right time to hatch into an adult.  These pupae are very resilient and are protected by their cocoon.  Pupae can survive quite a long time, waiting until environmental conditions and host availability are just right.  Then they emerge from their cocoons when they detect heat, vibrations and exhaled carbon dioxide, all of which indicate that a host is nearby.  The newly emerged adult flea can jump onto a nearby host immediately.  Under optimal conditions, the flea can complete its entire life cycle in just fourteen days.  Just think of the tens of thousands of the little rascals that could result when conditions are optimal!

Knowing this life cycle allows us to understand why it has always been important to treat both the host animal and the indoor and outdoor environment in order to fully control flea numbers.  Simply sprinkling some flea powder on your pet will not work; simply vacuuming the home vigorously will not work, simply placing a flea collar on your pet will not work.  There are a wide variety of flea products on the market today, but  the newer prescription products are finally taking the frustration out of flea control.  In some cases it is even possible to gain control by treating only the pet.  One of these products is called Program.  It is given orally once per month for dogs and cats, or by injection every six months for cats.  The adult flea is not harmed but the eggs she lays will not hatch, thus breaking the life cycle of the flea; with no reproduction the flea population eventually dissipates as long as the pet isn’t coming in contact with new fleas continually.  In warm climates, this treatment is typically year round, but in other climates treatment should begin in early spring before the flea season starts.  This may not be the product of choice for animals that are allergic to flea saliva (have flea bite hypersensitivity) since the adult fleas are not killed and are still able to bite the animal. 

There are four popular topically applied prescription products commonly used:  Advantage, Frontline PlusK9Advantix and Revolution… and each is unique.   Each of these products kills the adult fleas which are present on the animal.  The adult fleas often don’t even have a chance to bite the animal with these topical products which makes them a good choice for flea-allergic pets.  They are typically applied once per month, although Frontline Plus is labeled to control fleas on cats for one month and up to three months in dogs.  Frontline Plus also controls ticks when used monthly.   Revolution is labeled not only for use against fleas and ticks but also treats ear mites, sarcoptic mites (Scabies Mites) and Heartworm disease; your veterinarian will have specific preferences regarding each products’ most efficient usage.  For more information on these products, consult your veterinarian.  Technically speaking Program® (lufenuron) Flavor Tabs and Program® oral suspension are not prescription-only, although they are only made available through veterinarians.  Capstar® is approved for use in cats and dogs and is available through veterinarians and online at  It is not a prescription product.  Capstar is a tablet that kills fleas and does it very quickly.  It has no residual action and is useful if you want to quickly eliminate a new flea infestation before using a long term preventive. There are many other products which will kill fleas on the pet and for which no prescription is needed.  The drawback, however, is that some of these products may be less effective than the prescription products, but many really do help control flea populations.  These non-prescription flea products include flea shampoos, powders, sprays, mousses, dips, collars and spot-on products.

In the environment-Fleas on dogs and cats

The entire house is now ready to treat.  Several choices are available including sprays and foggers.  The most effective products are those which contain both an ingredient to kill adult fleas and an ingredient to kill the other life cycle stages.  The latter is called an insect growth regulator.  Methoprene is one such growth regulator.  Aerosol foggers may not penetrate well enough, in most cases, to kill all the hiding fleas and larvae.  Another option for indoor control is a sodium borate product that is applied to carpeting.  You should consider calling a local exterminating company for an estimate and a guarantee that their procedure will rid your premises of fleas.  Always follow exactly any label instructions for amount to use and methods of application.  Flea eradication won’t be cheap, either, but what price will you put on living free from flea infestations?

As for outdoor control, sprays and pelleted insecticides are generally used after dog houses and kennels are cleaned thoroughly.  An insect growth regulator is a good choice here as well.  Pyriproxifen, which is sold under the trade name Archer or Nylar, is more stable in sunlight and lasts longer outdoors than Methoprene.  It is important to know that the Environmental Protection Agency (EPA) has banned the insecticide Chlorpyrifos (Dursban).  Production ceased in December of 2000.  Certain non-toxic nematodes (tiny worms) can also be spread in areas of the yard which are warm and moist and which pets and fleas frequent.  The nematodes feed on the flea larvae.  And once there is a cover of snow on the ground, much of the major source of fleas is eliminated.

You should now be armed with the knowledge to prevent and control even the worst flea infestations which may come your way.  Be sure to consult your veterinarian regarding which methods and products will be best for you and your pets.  Your veterinarian will be your best source for current flea information.

Because of their giant size, fleas on dogs and cats can be a big problem that ends up spreading to other parts too. You might have noticed your pets acting unusual after being attacked by these parasites: they start scratching excessively, try hiding in places where it is very dark and even get depressed.

We offer various Flea control products such as shampoo and sprays to ensure you don’t have this problem again!

Frequently Asked Questions

What is the most commonly found flea on dogs and cats?

The domestic cat flea is the most prevalent species of flea found on domestic dogs and cats in North America. Ctenocephalides felis is the species’ official name. This flea species prefers humans, dogs, and cats as its hosts.

What kills fleas on dogs instantly?

Nitenpyram, also referred to as Capstar, is the substance that is most frequently used to quickly kill fleas on dogs. Fleas are killed by this single-use pill within 30 minutes of oral administration.

Where do dogs and cats get fleas from?

A cat or dog that is infected, as well as contaminated dirt or trash, might give your dog fleas. Due of the lack of barriers preventing them from dispersing the bothersome parasite far and wide, feral cats are frequently found to be flea transmission sources.

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