The 5 Different Ways Dogs Get Fleas (And How to Get Rid of Them)

© Cosmin Manci/

Written by Sharon Parry

Updated: October 30, 2023

Share on:


Listen to Article

Fleas are one of the most common and annoying issues that affect domestic dogs. But how do dogs get fleas and what can you do to prevent it? Fleas are parasites that live on a dog’s skin and can be quite tricky to get rid of. The best approach is to stop your dog from getting a flea infestation in the first place.

Dogs get fleas from other animals, the environment (inside and outside your home), and even from people and possessions. Eggs, larvae, and adult fleas can be the source of your dog’s infestation. Treatment can be prescription or non-prescription chemicals that can be administered in many different ways ranging from shampoos to tablets.

Why You Should Be Concerned About Dog Fleas

On the face of it, dog fleas don’t seem like something that you should have to worry about! They are only about an eighth of an inch long and do not have wings so they can’t even fly onto your dog.

But these pests can do a lot of damage. They feed off your dog’s blood ( as well as skin flakes, poop, and plant matter) and as they feed they inject saliva into their canine host. This causes irritation because most dogs are allergic to flea saliva. The constant scratching leads to skin trauma and then to infections. Diseases and other infestations including tapeworms and rickettsiae can also be transmitted in this way.

Fleas may not be able to fly but they can certainly jump! They have very large rear legs in proportion to their body and can travel at least 12 inches in one leap. They are also very numerous – a single female flea can produce 2,000 eggs in her lifetime. Experts estimate that for every adult flea you find on your dog, there are 100 immature fleas in the process of developing!

Depending on temperature and humidity, the entire life cycle of the flea can be completed in as little as 12 to 14 days or last up to 350 days. However, under most conditions, fleas complete their life cycle in 3 to 8 weeks.

There are thousands of species of flea on the planet but in the US the two most common are the cat flea and the dog flea. You may be surprised to know that the flea that you are most likely to find on your dog is actually the cat flea – Ctenocephalides felis as these are most common.


Fleas reproduce quickly and can cause your dog unending irritation.


The 5 Different Ways Dogs Get Fleas

How do dogs get fleas? To understand this fully, we need to consider the whole lifecycle of the flea – Ctenocephalides felis. Cat fleas need warmer temperatures which is why they are more of a problem in warmer climates and in the summer months. These are the most common ways in which these pesky parasites can get onto your dog’s body.

Flea Lifecycle

They begin to reproduce at around two days old. The female mates immediately after their first meal of blood from a cat or dog’s skin. She lays up to 50 tiny white oval eggs a day which can easily fall off the dog/cat and onto soil, carpets, and bedding. The eggs hatch into larvae within 1-6 days and move around to feed on organic debris (like skin flakes) or on the poop of adult fleas.

They don’t like bright light so they tend to lurk deep within carpet fibers and in nooks and crevices in furniture as well as under grass and branches or in soil. Larvae need a moist environment that has over 50% humidity to survive but they are very good at traveling as far as several feet to find a habitat that suits them. They love deep carpets, cracks between floorboards, and damp basements.

They will only develop into fleas if they are in a shaded moist area and this is usually about a week after hatching but they can stay as larvae for up to 3 weeks if the environmental conditions are not favorable. The larvae form cocoons within which they pupate into fleas. Larvae usually spend up to 2 weeks in the cocoon but it can be up to a year.

Newly emerged fleas must find a host to feed on within two weeks and it is these that hop onto dogs (and people) and bite them. They will then prefer to stay on the same host and breed so the whole cycle starts again.

#1 Other Animals in Your Home

Adult fleas can use their powerful hind legs to jump from one pet to another. They can lay eggs on your dog and then may jump back off. Fleas will leap from cats onto dogs. The cat does not even have to be your cat, it could be visiting in your garden. It is important that you treat all the cats and dogs in your home for fleas at the same time.

Have you had any canine visitors to your home recently? They may have introduced the problem unintentionally.

dogs in home

Various animals can bring fleas into your home, including (of course), other dogs.

©Eric Isselee/

#2 Human Visitors

Flea eggs and cocoons can survive for months. They can live on clothing and articles that belong to humans. Have you had any visitors that have a pet (even if they did not have the pet with them)? They could have carried eggs and pupae into your home. This is also the case if they work with animals or even if they work outdoors in grassy areas. This could even apply to you!

#3 Other Animals in Your Neighborhood

Most dogs love to be sociable and get up close and personal with other dogs in your area. This can be in the dog park or on the sidewalk. Don’t forget that fleas can jump up to 12 inches so another dog with fleas does not have to be that close to cause a problem for your dog. The same is true if your pooch likes to check out friendly cats or even wildlife too. Birds, rodents, foxes and deer can all carry fleas that can infest dogs.

#4 The Outdoor Environment

Flea larvae prefer sheltered, moist areas so your own backyard and garden are ideal hiding places. The fleas could have entered your property on birds and other wildlife but are now in a great location to infest your dog.

Fleas and eggs fall off infested dogs all the time, so environments that have a high concentration of dogs are also likely to have plenty of fleas. Dog parks and any outdoor area that is popular with dog walkers would be included in this.

#5 Kennels or Groomers

Kennels and groomers are other locations where there are a lot of dogs. Even if the owners insist that their canine clients have been flea-treated, some can sneak in. If you have recently boarded your dog in kennels or taken them to a groomer, this could easily be the source of their infestation.

How Do Dogs Get Fleas After Treatment?

It can be so frustrating when you have carried out a thorough flea treatment and your dog is still scratching like mad. One reason for this is that they have residual irritation and possible infection even though the fleas have gone. It is best to check this out with your vet.

However, there are several other potential reasons. You may have chosen the wrong product for your circumstances, you may have used the product incorrectly or you may not have used it for long enough. Natural remedies are rarely powerful enough to control an active flea infestation so bear this in mind. If you are using store-bought products containing pyrethroids, it is possible that the fleas have developed a resistance to it.

Dogs can also get re-infested from your home – it can take up to 6 months of treatment to eradicate fleas from a dwelling. If your dog has no active flea protection, they can get continually re-infested during this time.

How to Get Rid of Fleas on Dogs

Now that you know how your dog got fleas in the first place, it’s time to look at how to get rid of them. There are some highly effective treatment products and many of them also act as a deterrent for fleas so your dog does not pick up another infestation. They may work in different ways. Some will target just adult fleas but others are effective against larvae and eggs and therefore break the lifecycle of the flea.

Some are part of combined treatments that also protect a dog against worms and ticks. Your vet is always the best source of advice on which product is best for your dog. In most climates, flea treatment is recommended all year round even though the fleas are more prevalent in the warmer months.

Here is an outline of your options.

Prescription Flea Products

Prescription flea medications are generally regarded as the most effective but they can also be the most expensive and you can only get them from your vet.

Some are applied topically (to the skin) and others are taken orally. Examples of active ingredients are fluralaner which starts to kill fleas within a couple of hours and lasts for three months and spinosad which starts working in half an hour and lasts for one month.

There are some dogs that are highly sensitive to flea saliva and therefore need a product that targets adult fleas as well as eggs and larvae. These dogs also need a product that contains a flea-repellant so that no new fleas will leap on them and bite them. These are available as collars or medication.

Non-prescription Flea Products

Non-prescription flea products are much easier to get hold of and are usually cheaper but they may not be as effective. There are lots of different types:

  • Flea collars
  • Flea sprays
  • Flea shampoos
  • Flea powders
  • Topical (spot-on) flea treatment
  • Oral flea treatments

It is up to you to choose which method of treatment is best for you and your pet. Some, such as oral treatments, are mess-free. Others, such as shampoos, remove fleas but do not prevent new fleas from jumping onto your dog.

How to Control Fleas in the Environment

Flea treatment cannot be fully effective unless you also take steps to control fleas in the environment – inside and outside your home.

Treating Fleas Inside Your Home

If you discover that your dog has a flea infestation, at the same time as treating them, you need to do the following:

  • Wash all your dog’s bedding in hot, soapy water
  • Vacuum carpets and rugs thoroughly and empty the canister or throw away the bag and take the trash bag outside
  • If possible, steam-clean carpets, rugs, and soft furnishings
  • Apply an environmental flea treatment. Foggers can be highly effective. If you have young children, you may prefer a product that contains boric acid rather than chemicals that persist in the environment. Always read the label to make sure that you keep children and pets safe.
  • Preferably choose a product that does not just kill adult fleas. If you choose one with a growth regulator, it will also kill the other life cycle stages and offer greater protection.
  • Popular choices are Methoprene and sodium borate.
  • If you are not successful, consult a professional pest control company.

Treating Fleas Outside Your Home

Treating fleas outside involves a careful balance of effectively removing fleas whilst not releasing dangerous chemicals into the environment. To help achieve this, the Environmental Protection Agency (EPA) banned the insecticide chlorpyrifos (Dursban) and it has not been produced in the US since December 2000.

Most outdoor treatments are in the form of sprays and pellets but treatment should be carried out alongside thorough cleaning of outdoor dog houses and kennels. Pyriproxifen is a popular choice because it is a growth regulator and is quite stable in sunlight.

If you are worried about using toxic substances around vegetable gardens or if you have young children, Diatomaceous earth products are a good choice. An organic option would be to purchase some special tiny worms that feed off flea larvae. Nature can also be on your side. A hard frost or a good coating of snow will remove most fleas, eggs, and larvae from the environment!

Summary of The 5 Different Ways Dogs Get Fleas

NumberWays Dogs Get Fleas
1Other Animals in Your Home
2Human Visitors
3Other Animals in Your Neighborhood
4The Outdoor Environment
5Kennels or Groomers
Summary Table of The 5 Different Ways Dogs Get Fleas

Can Fleas Jump From Dogs to Humans?


Causing intense itching, fleas are a nuisance to humans and pets alike.


Fleas are able to jump from dogs to humans and are also able to reside in areas that humans live in, like homes and yards. However, even though they are able to jump on humans, and often do, they do not stay there like they do with animals. Unlike dogs, fleas won’t reside on humans, either on their skin or their hair, and after a brief visit, will jump off.

Humans don’t provide the right kind of environment or the proper food source that fleas look for. Although fleas will bite you and they typically do it multiple times before they move on. Flea bites most often occur closer to the bottom of your legs, feet, and ankles, and will appear as small, red bumps that are usually itchy. Fleas need animal blood to survive so even if they are on your furniture, they can’t live unless they have your pet to live on.

Ready to discover the top 10 cutest dog breeds in the entire world?

How about the fastest dogs, the largest dogs and those that are -- quite frankly -- just the kindest dogs on the planet? Each day, AZ Animals sends out lists just like this to our thousands of email subscribers. And the best part? It's FREE. Join today by entering your email below.

What's the right dog for you?

Dogs are our best friends but which breed is your perfect match?


If you have kids or existing dogs select:

Other Dogs

Should they be Hypoallergenic?

How important is health?
Which dog groups do you like?
How much exercise should your dog require?
What climate?
How much seperation anxiety?
How much yappiness/barking?

How much energy should they have?

The lower energy the better.
I want a cuddle buddy!
About average energy.
I want a dog that I have to chase after constantly!
All energy levels are great -- I just love dogs!
How much should they shed?
How trainable/obedient does the dog need to be?
How intelligent does the dog need to be?
How much chewing will allow?

Share this post on:
About the Author

Dr Sharon Parry is a writer at A-Z animals where her primary focus is on dogs, animal behavior, and research. Sharon holds a PhD from Leeds University, UK which she earned in 1998 and has been working as a science writer for the last 15 years. A resident of Wales, UK, Sharon loves taking care of her spaniel named Dexter and hiking around coastlines and mountains.

Thank you for reading! Have some feedback for us? Contact the AZ Animals editorial team.