How To Get Rid Of Fleas On Dogs

By Dr. Kaitlin Wurtz June 20, 2020

More than 2,000 species of fleas exist worldwide. Fortunately for us, only around 300 of these species are found in the United States, and only a few of these species use dogs as a host (Zentko and Richman, 2014). The most prevalent flea found on dogs in America is Ctenocephalides felis, or the cat flea. These external parasites survive by drinking blood from warm blooded bodies including humans, but they prefer hairier animals such as our furry pets, rodents, raccoons, opossums, and skunks (Rust, 2017). Since fleas can be damaging to our pet’s health and wellbeing, pet owners should take preventative measures to keep fleas out of their house and off their pets. Fleas can cause skin irritation, bacterial infections, can transmit tapeworm, and can even result in anemia in severe cases (Jellison, 1959).

What Do Fleas Look Like On Dogs?

Fleas are tiny little creatures, about 1/8 of an inch long, and can just barely be seen with the naked eye. Look for small, reddish-brown bugs with thin bodies, no wings, and long back legs that they use for jumping. Look carefully because fleas can be fast moving and difficult to see on dogs that don’t have pink skin. If you think your dog has fleas but you are struggling to see the fast-moving tiny insects, there are a few other indicators that you can look for. One visibly noticeable sign that your dogs has taken up fleas as residents is the presence of what is often referred to as ‘flea dirt’. This is really just a nicer way to say flea feces. Flea dirt looks sort of like pepper. It is black to brown in color and will turn brighter red when rehydrated on a wet paper towel. Since fleas consume blood, their feces will essentially be dried up blood components. You may find flea dirt on your dog’s skin, bedding, carpeting, or furniture. 

How Do Dogs Get Fleas?

Dogs can get fleas from other infected animals or they can pick them up from the environment. Adult fleas feed and breed on animal hosts. During this stage they can use their powerful back legs to jump onto other nearby animals. When these adult fleas lay eggs, these small, round eggs fall off into the environment. The eggs will then hatch, become larva, then enter a pupa stage, and finally mature into adults (CDC, 2017). Fleas will seek out humid, shaded areas such as grass outdoors, or carpets and furniture indoors, where they will wait for their next host to pass by within jumping range. A single female flea has been known to lay over 20 eggs in a single day (Kern et al., 1997). It is not difficult to imagine how flea infestations can get bad extremely quickly.

How Do You Know If Your Dog Has Fleas?

Typically, the first indicator of fleas is when a dog displays excessive scratching. Flea bites are painful, and flea saliva can cause skin irritation. Additionally, you may notice hair loss or thinning hair, bald spots, inflamed areas, or scabbing from your dog scratching and biting at their irritated skin. If you notice any of these signs of a potential flea infestation, check your dog’s body over carefully for adult fleas, flea dirt, or small white specks (flea eggs). If you do find fleas, consult with your veterinarian to determine a treatment plan.

How To Get Rid Of Fleas On Dogs

Getting rid of fleas on dogs can be quite the process. Fleas are not isolated to just your dog’s body. They rely on the environment to complete their lifecycle. Therefore, to completely rid your dog and home of fleas, you will need to target the multiple life stages present on your dog, in your home, and in outdoor areas that your dog regularly frequents. Cat fleas, the most prevalent flea species in the United States, complete their life cycle in approximately 30-70 days. However, this can vary widely depending on the temperature and humidity levels (Zentko and Richman, 2014). This means it could take months of regular cleaning and treatments to completely clear up a flea infestation. This is why preventative flea measures are highly recommended. When shopping for flea preventatives or treatments, carefully read the product ingredients and instructions to fully understand which life stage of the flea the product is designed for. Effective treatments involve killing the adult fleas, halting the development of immature fleas, and keeping the environment clean to prevent future outbreaks. The following are different treatment options that are available over the counter or from your veterinarian.

  • Flea Shampoos
    • What Is It?
      Flea shampoos are shampoos formulated with chemicals that kill fleas on contact. Common active ingredients include pyrethrins, carbamates, and citrus peel derivatives (Zentko and Richman, 2014).
    • How Do You Use It?
      Carefully read and follow the instructions listed on the shampoo bottle. Most shampoos recommend wetting your dog, applying the appropriate amount of shampoo, sudsing up your dog’s entire body (avoiding the face), letting the product sit on your pet for a period of time, and finally thoroughly rinsing your pet to ensure that no product is left behind that can irritate your dog’s skin.
    • How Effective Is It?
      The efficacy of flea shampoos are sometimes questioned (Armstrong et al., 2015). Some believe that regular shampoos may just be as effective at removing fleas and pose a lower risk of adverse reactions. The downside to flea shampoos is that they only remove the fleas currently on your dog’s body. As soon as your dog is bathed, new fleas from the environment can hop right back on.
  • Flea Sprays
    • What Is It?
      Flea sprays are liquid products that often contain insect growth regulators such as methoprene and pyriproxyfen.
    • How Do You Use It?
      These products can come in aerosol or pump bottles. They are designed to be sprayed directly on to your pet’s body. The product should be applied to the face carefully using a cotton ball to avoid contact with your pet’s eyes or mouth. Make sure you use these products in a well-ventilated area to avoid inhaling toxic fumes. Many of these sprays can also be used throughout the home.
    • How Effective Is It?
      Flea sprays are effective at preventing the development of juvenile fleas into adults. Some products also contain chemicals to kill adult fleas. Since the product can be used to treat the animal and the environment simultaneously, they are more effective than a product that only treats a single life stage of fleas on the animal.
  • Topical Treatments
    • What Is It?
      Topical treatments are liquids or gels that get applied directly to your dog’s skin. Common active ingredients include permethrin, fipronil, imidacloprid, spinosad, metaflumizone, and selamectin (Hillestad, n.d.).
    • How Do You Use It?
      These products are often sold in small tubes for easy application. Read and follow the directions on the label for your specific product. The instructions will often recommend squeezing the product onto a spot on your dog’s back between their shoulder blades so they can’t lick it off. Make sure to purchase a product designed for your dog’s body weight to avoid accidently poisoning your dog.
    • How Effective Is It?
      Most topical treatments are effective for about a month. One study found spot treatments to be 88.4% effective over a 90 day study period (Dryden et al., 2013). Depending on the ingredients, they can kill adult and larval stages of fleas and can prevent new fleas by repelling them. Again, these treatments only take care of fleas on your pet. Additional measures would be needed to remove fleas from the environment.
  • Oral Flea Treatments
    • What Is It?
      Oral flea treatments work in different ways depending on their active ingredients. Some can be effective in killing adult fleas in as little as 30 minutes (Tinembart and Tashiro, 2000). Others contain insect development inhibitors which disrupt egg and larval development.
    • How Do You Use It?
      These treatments are given as a pill or a chewable tablet. Some products, such as those that target adult fleas, may need to be given daily. Other products such as those designed to target earlier life stages, may only need to be given once a month.
    • How Effective Is It?
      Oral flea treatment’s effectiveness depends on the product itself. One study found oral treatments to be 99.9% effective (Dryden et al., 2013). To eliminate fleas that are already present, oral treatments will need to be used alongside other treatments to target multiple life stages and the environment, over a prolonged period of time. Oral flea products that work to prevent flea outbreaks are incredibly effective when used appropriately.
  • Flea Collars
    • What Is It?
      Flea collars are collars that have been infused with insect growth regulators such as methoprene and pyriproxyfen or flea deterrent chemicals. There are also other collars on the market that emit ultrasonic pulses to deter fleas.
    • How Do You Use It?
      Flea collars are worn around the dog’s neck just like any other collar. Make sure that the collar is designed for your pet’s age and weight. Puppies may need a lower dose. Thoroughly wash your hands with soap and water after handling the collar. Flea collars should be applied snugly while still allowing for two fingers to fit between the collar and their neck. Cut off any extra length from the collar to prevent your dog or other pets from chewing on it. Check often for irritation under the collar. Dogs may become sensitive to these chemicals overtime and irritation may be hidden under the collar.
    • How Effective Is It?
      In practice, flea collars may not be as effective as advertised. They may lose their potency over time, especially when exposed to soap and water (Stanneck et al., 2012). Flea collars may not be the best option for dogs that swim or are bathed often. Moreover, there is a lack of conclusive scientific evidence for the effectiveness of ultrasonic flea repellants (Bonge, 1990).
  • Flea Combs
    • What Is It?
      A flea comb is a fine come that lets hair pass through, but captures larger debris such as fleas, flea dirt, and flea eggs. Look for a comb that has 32 teeth per inch.
    • How Do You Use It?
      First detangle your dog’s hair if they have a long coat. Then methodically work your way across your dog’s entire body with the comb. Dunk the comb in a detergent after each pass to clean off any fleas or flea products that were captured.
    • How Effective Is It?
      Flea combs are very effective at removing fleas from the dog’s body. Combing a dog can be time consuming, but it is a safe, chemical free option that should be considered. Flea combs are recommended for use on ill, pregnant, or young animals that may be sensitive to the harsh chemicals often found in other products. Like many other treatments, flea combs should be used in conjunction with other products that remove fleas from the environment and target the different life stages of fleas.
  • Natural Flea Treatments for Dogs
    • What Is It?
      Many natural remedies for treating fleas can be found online. These include things such as feeding brewer’s yeast, supplementing with vitamin B, using geranium, eucalyptus, garlic, or onion. Pennyroyal oil is another natural product that is available in shampoos.
    • How Do You Use It?
      These products are used in a variety of ways including being administered orally or topically.
    • How Effective Is It?
      Unfortunately, there is a lack of evidence as to how effective these treatments are. Always consult with your veterinarian before trying a natural remedy. Some may have serious health consequences for your pet. For instance, pulegone, the active ingredient in pennyroyal oil shampoo has dose related toxic effects on mammals which may include lethargy, vomiting, diarrhea, nose bleeds, seizures, and possible death due to liver failure (Zentko and Richman, 2014). 

How Do I Prevent My Dog From Getting Fleas In The Future?

Flea infestations can be prevented through the combined use of flea preventatives and keeping a clean environment. Work with your veterinarian to determine which flea preventative is best for you and your dog. Monitor your pet regularly for any signs of fleas such as scratching, biting or licking. Consider bathing your pet after an outing or play date that may have exposed them to fleas. Keeping your home clean can also reduce the chance of a flea outbreak by removing eggs or developing fleas from the environment. Wash your dog’s bedding, collars, and plush toys often as these may be home to young, developing fleas. Keep the area around your home clean to prevent attracting rodents or other animals that can carry fleas and spread them to your dog. Vacuum floors and furniture often to pick up existing flea eggs that may have fallen off your pet. Mop floors with soapy water to kill any fleas that are present. Carpet powders or sprays may help kill any fleas that were left behind by the vacuum. Don’t forget to clean out your car if your traveled with your dog recently. Cleaning the environment is most effective when everything can be cleaned together in a relatively short period of time.


By understanding the life cycle of fleas, we can most effectively eliminate them from our homes and prevent them from reappearing in the future. A combination of killing adult fleas, preventing young fleas from developing, using flea repellants as a preventative measure, and maintaining a clean environment can keep your dog happy, healthy, and free from harmful fleas.

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Works cited

Armstrong, R. D., Liebenberg, J. E., Heaney, K., & Guerino, F. (2015). Flea (Ctenocephalides felis) control efficacy of topical indoxacarb on dogs subsequently bathed with a chlorhexidine–ketoconazole shampoo. Australian veterinary journal, 93(8), 293-294.

Bonge, N. J. (1990). Opposing viewpoints on efficacy of ultrasonic flea collars. Journal of the American Veterinary Medical Association, 196(9), 1354-1355.

CDC - DPDx - Fleas. (2017, December 08). Retrieved June 19, 2020.

Dryden, M. W., Ryan, W. G., Bell, M., Rumschlag, A. J., Young, L. M., & Snyder, D. E. (2013). Assessment of owner-administered monthly treatments with oral spinosad or topical spot-on fipronil/(S)-methoprene in controlling fleas and associated pruritus in dogs. Veterinary parasitology, 191(3-4), 340-346.

Hillestad, K. (n.d.). Flea Control and Prevention. Retrieved June 18, 2020.

Jellison, W. L. (1959). Fleas and disease. Annual review of entomology, 4(1), 389-414.

Kern Jr, W. H., Koehler, P. G., & Patterson, R. S. (1992). Diel patterns of cat flea (Siphonaptera: Pulicidae) egg and fecal deposition. Journal of medical entomology, 29(2), 203-206.

Rust, M. K. (2017). The biology and ecology of cat fleas and advancements in their pest management: a review. Insects, 8(4), 118.

Stanneck, D., Kruedewagen, E. M., Fourie, J. J., Horak, I. G., Davis, W., & Krieger, K. J. (2012). Efficacy of an imidacloprid/flumethrin collar against fleas, ticks, mites and lice on dogs. Parasites & vectors, 5(1), 102.

Tinembart, O., & Tashiro, S. (2000). Capstar (nitenpyram): a new systemic flea adulticide for dogs and cats. Agrochemical Japan, 76, 7-10.

Zentko, D., & Richman, D. (2014, December). Featured Creatures: Cat flea. Retrieved June 19, 2020.