How to Handle Fleas on Dogs

When pet owners are asked what they dread most about the summer months, the topic that invariably comes up most is fleas! 

These small, dark brown insects prefer temperatures of 65-80 degrees and humidity levels of 75-85 percent—so for some areas of the country, fleas on dogs are more than just a summer problem. In many areas of the southern United States, fleas can survive and bother your pet year-round.

Dogs 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 surrounding environment onto the host. (Fleas do not have wings, so they 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. It can lead to severe scratching and chewing that causes hair loss, inflammation and secondary skin infections. Some pets can be hypersensitive to the flea's saliva and will itch all over from the bite of even a single flea.

How to Spot Fleas on Dogs

How do you know if fleas are causing all that itching (pruritus in veterinary terms)? Generally, unlike the burrowing, microscopic Demodex or Scabies mites, fleas can be seen scurrying along the surface of the skin.

Fleas are a dark copper color and about the size of the head of a pin. They dislike light, so your best chance of spotting fleas on a dog is to look within furry areas and on the belly and inner thighs.

"Flea dirt" can also signal that there are fleas on a dog. Flea dirt looks like dark specks of pepper scattered on the skin’s surface. If you see flea dirt—which is actually flea feces that is composed of digested blood—pick some off the pet and place on a wet paper towel. If the tiny specks spread out like a small bloodstain after a few minutes, it's definitely flea dirt, and your pet has fleas.

What Is the Best Way to Get Rid of Fleas on a Dog?

If you've discovered that your dog has fleas, here are a few things you can do to provide your pet with relief.

Oral and Topical Flea Control

Fleas are annoying and persistent. However, dog flea and tick pills and other spot-on dog flea and tick treatments have proven to be some of the fastest ways to rid your pet of fleas.

Some only target adults, while others target flea eggs, larvae and adult fleas, so it's important to buy the right one. Others will combine flea control and heartworm prevention in one treatment. You’ll notice that some require a prescription, while others do not.

So, what is the best oral flea treatment for dogs? It will depend on your individual dog's needs. Talk to your vet about which option is the best for your pet.

Prescription Flea Medications

There are a wide variety of flea products on the market today, but the newer prescription flea and tick products are finally taking the frustration out of flea control with popular and highly effective brands.

Talk to your veterinarian about preventative flea and tick medicine for dogs, as many are prescription products. Prescription treatments present one of the best ways to kill fleas fast.

Bravecto (fluralaner) begins to kill fleas within two hours and lasts for three months, while products containing spinosad (Comfortis, Trifexis) begin to work within 30 minutes and last for one month.

Some of these flea products do not harm the adult flea but instead prevent her eggs from hatching, 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, prescription flea and tick treatment for dogs is typically a year-round endeavor, but in other climates, treatment should begin in early spring before the flea season starts.

For animals that are allergic to flea saliva (have flea bite hypersensitivity), choose a product that targets adult fleas as well, since they are still able to bite the animal. For dogs with flea hypersensitivity, products containing a flea repellent (Seresto collar, Vectra 3D) are the best choice so that the fleas never bite.

Nonprescription Medication to Treat Fleas on Dogs

There are also many other products which will kill fleas on the pet and for which no prescription is needed. The drawback, however, is that these products may be less effective than the prescription products.

These nonprescription flea products include flea shampoos, flea powders, flea sprays, flea collars, oral flea treatment and spot-on products. Many veterinarians are reporting that their patients still have fleas after use of these over-the-counter products, but there are also good reviews from pet parents for some of these products.

Capstar, for instance, is a tablet that kills adult fleas and is taken orally. It begins to work within 30 minutes, and kills more than 90 percent of all fleas within four hours. It is used to treat flea infestations.

Dog Flea Shampoos

There are several dog flea and tick shampoo options for dogs and cats on the market that can be quite effective when used properly. Flea dog shampoos may contain a variety of ingredients that are more or less effective.

Small puppies should only be bathed in nontoxic dog shampoo. You’ll need to consider whether or not your pet can stand getting soaking wet and being lathered up for five to 10 minutes, though, since that's how long the shampoo takes to sink in.

Following a nice warm bath, you'll have killed the fleas and will be able to use a dog flea and tick comb to remove the dead fleas from your dog. However, flea shampoos do not protect your dog from continued infestation with fleas.

WARNING: Tea tree oil is toxic. Do NOT use tea tree oil as a flea repellent in cats or dogs.

Understanding the Flea Life Cycle 

But your quest to eliminate fleas isn’t over just yet—you also have to treat the environment. Simply sprinkling some flea powder on your pet will not work; simply vacuuming the home vigorously will not work, simply placing a dog flea collar or using a flea topical on your pet will not work.

In order to understand how each treatment options works and why you must also treat the environment, we must first understand the flea’s life cycle. The various treatment and prevention products work on different parts of this life cycle.

There are several stages to the flea life cycle: egg, larva, pupa (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. The life cycle can take anywhere from two weeks to a year.

The flea's host is a warm-blooded animal such as a dog or cat (or even humans). The various flea stages are quite resistant to freezing temperatures. The adult female flea typically lives for several days to weeks on its host. During this time period, she will suck the animal’s blood two to three times and lay 20 to 30 eggs each day. She may lay several hundred eggs over her life span. These eggs fall off of the pet and 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 eggs then hatch 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. They 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 14 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.

You must also treat the home and surrounding area.

How to Treat Fleas in the Environment

With any flea treatment, it is necessary to treat all of the animals in the home in order to achieve complete success. In addition, you will likely need to treat the indoor and outdoor environment.

Treating the Home

When treating the indoor environment, it is important to wash all bedding in soapy, hot water. All of the carpeting should be vacuumed thoroughly, and the vacuum bag thrown away or canister emptied and trash bag taken outside. Steam cleaning the carpet can kill some of the larvae as well. Remember, though, that vacuuming and shampooing a carpet will still leave a good percentage of live fleas, so some sort of chemical treatment may be necessary.

The entire house is now ready to treat for fleas. Several choices are available including highly effective foggers. Boric acid-based products may be a safer option for homes with small children or other situations where chemical residues are a concern. 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 some 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.

Flea eradication won't be cheap, but what price will you put on living free from flea infestations?

Outdoor Flea Control

As for outdoor control, sprays and pelleted insecticides are generally used after dog houses and dog kennels are cleaned thoroughly. An insect growth regulator is a good choice here as well. Pyriproxifen 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.

Diatomaceous earth, a nontoxic option, can be very effective and is safe to use in and around vegetable gardens and children’s outdoor play equipment. When choosing a diatomaceous earth product look for a food-grade product like DiatomaceousEarth Food Grade Powder, which is safe for use around pets.

Certain nontoxic 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.

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.

PetMD Editorial