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How Do Dogs Get Fleas? (8 Ways Fleas Infest Dogs)

Dogs get fleas from direct contact with people and other animals or from the environment. The environment includes the Dog Park, garden, house, or any other place that is infested with fleas.

Fleas are the most common dog parasites and even pose a danger to animal health in some cases. 

Not only are fleas unwanted guests, but they also feed on your dog’s blood and multiply extremely quickly. Even if you only see a single flea in your dog’s fur, there is a good chance your dog also has flea eggs.

These external parasites can infest your home, resulting in constant flea infestations on your dog. Your dog can then pass fleas on to other pets, or spread flea eggs in the environment around it.

In this article, you will learn where fleas come from, why dogs get fleas, if fleas are dangerous to your dog’s health, and more.

How Do Dogs Get Fleas?

A dog can get fleas in many ways, the most common being in direct contact with fleas in the environment and other infected animals. Dogs most often get fleas from cats, especially strays.

To understand how your dog can get fleas, you need to know fleas’ four evolutionary stages:

  1. Egg
  2. Larva
  3. Pupa
  4. Adult fleas

Only adult fleas feed on blood and live on your dog. The other evolutionary stages live in the environment, but there are also cases where flea eggs or larvae have been found on dogs (known as accidental parasitism).

Dogs primarily get fleas from four places:

  1. From other animals.
  2. From the environment.
  3. Other pets in the house.
  4. From the people who come to visit or from you.

1. Fleas From Other Animals Outside

Fleas From Other Animals Outside

Dogs can become infested with fleas when they come in contact with animals that live outside.

Common outdoor animals that infest dogs with fleas are:

  • Other pets
  • Stray animals
  • Wild animals

Fleas can jump up to 8 inches vertically (20 cm) and 13 inches horizontally (33 cm).[1] This means fleas can jump on your dog, as long as your dog is near other infected animals.

2. Fleas From the Environment

Dogs can get fleas not only through direct contact with an infected animal but also from direct contact with fleas in the environment, whether it is indoors or outdoors. 

Fleas and their eggs get into the environment when they jump or fall from an infested animal.

Dogs can get fleas when playing in the grass, leaves, or other places, as fleas tend to live in these places.

Common places dogs attract fleas from include:

  • Gardens
  • Infested houses
  • Dog Parks
  • Kennels
  • The groomer

Fleas In the Grass in Your Yard

Fleas In the Grass in Your Yard

Even if your dog is the only one using the yard, fleas can come from wild animals that pass by, such as rats, rabbits, squirrels, deer, and others. Their fleas can jump into the grass, waiting to feed on a new host.

Fleas In the Dog Park

Parks and other areas with high concentrations of dogs are reservoirs of fleas. Fleas either jump from one dog to another or jump on the ground and then to your dog.

Fleas From the Kennel or Groomer

Fleas can be a problem in places where many dogs circulate, such as kennels, pet hotels, or groomers. It only takes a few fleas to result in a massive infestation.

Not all pet owners who take their dogs to a pet hotel or groomer apply measures to kill the fleas on their beloved quadruped, resulting in the spreading of this parasite.

Although flea treatment and prevention methods are constantly applied by the staff members in all of these locations, these external parasites can still be present and can infest other pets.

Fleas In the House

If a flea has laid eggs on your dog, the eggs will fall off, typically in the house. The most common place for dogs to be reinfested with fleas is their bed. Because your dog spends most of the time in its bed, most of the flea eggs drop there.

At the right temperature and humidity, eggs hatch and evolve into the next biological stages, repeating until they become adult fleas. Freshly metamorphosed fleas are starving and look for a host to feed on, often being your dog.

3. Fleas From Other Animals in Your House

Fleas From Other Animals in Your House

All pets in your household can represent a common source of fleas. They can pass fleas from one to another. A single infested pet can transmit fleas to the rest of your pets.

As eggs fall into the environment, they hatch at a later date and become adult fleas that can infest your other pets as well.

Check all your pets for fleas or flea dirt and take the necessary measures.

4. Fleas From Visitors or You

If your dog has recently become infested with fleas, think about who visited your house recently and whether they have pets at home. 

Another scenario is when you or your visitors bring fleas on your clothes and footwear. You can bring fleas home from the park, garden, etc.

Newly-Hatched Fleas

Houses undergoing flea eradication represent a danger to dogs. Eradication treatment lasts between 3-6 months because fleas in the pupa stage are resistant to pesticides.

If you have passed by or entered a house during eradication with your dog, the fleas in the pupae can infest both you and your dog.

Why Do Fleas Get on Dogs?

New-born fleas are immediately attracted to heat, light, vibrations, and carbon dioxide. In the first week of a flea’s life, it actively seeks out a host to feed.[2]

Although it doesn’t matter what kind of dog they feed on, fleas usually prefer long-haired dogs. They are able to hide and feel protected in the dog’s long fur, unlike short-haired breeds where fleas are more exposed.[3]

Why Do Fleas Get on Dogs

Why Does My Dog Have Fleas Even Though I Treated Him?

Your dog can still have fleas after flea treatment if the treatment was ineffective or the antiparasitic substances have not yet taken effect.

There are three situations where dogs can have fleas after treatment:

  1. The product you used was ineffective.
  2. It takes a while to get rid of fleas.
  3. The product has not yet taken effect.

1. The Product You Used Was Not Effective

It is possible that the product you used was of poor quality, or you used an improper product for your dog’s weight and age.

This can also happen if you use natural remedies to combat fleas instead of antiparasitic substances.

2.  It Takes a While to Get Rid of Fleas

Homemade Flea Shampoo Recipes For Dogs

Most flea treatments only kill adult fleas, not their eggs or larvae. It takes fleas about two weeks to become adults, which is why it also takes flea treatment at least two weeks to remove all fleas.

If you have applied a product that only kills adult fleas, the eggs and larvae can reinfest your dog. It takes about a month to completely remove fleas on your dog.

This is why it is recommended to treat your house for fleas too. This is especially true for the place where your pet sleeps.

3. The Product Has Not Yet Taken Effect

The Product Has Not Yet Taken Effect

It takes about 48 hours for classic antiparasitic products to take effect. During these two days, you will still find fleas on your dog.

Externally applied antiparasitic products (spot-on pipettes or collars) release chemicals that spread throughout your pet’s body through the oils on its fur and skin, creating a reservoir in the sebaceous glands. The substances in these reservoirs are released gradually over a period of time, depending on the product.

How Often Should I Treat My Dog for Fleas?

Depending on the chosen product, you can treat your dog for fleas as follows:

ProductApplication period
Spot-on pipettesOnce every 4-5 weeks.
Antiparasitic collarsOnce every 4-8 months, depending on the product.
Chewable tabletsOnce every 4-5 weeks or three months, depending on the product.
SpraysOnce every 4-5 weeks, depending on the product.


How Quickly Can a Flea Infestation Occur?

A flea infestation can occur as quickly as two weeks if environmental conditions are ideal for fleas. Otherwise, it can take up to a month or a few.

 Can My Dog Get Fleas From Grass?

Yes, your dog can get fleas from the grass, leaves, debris, and so on. Fleas usually jump from an animal into the environment after feeding.

About Iulia Mihai (DVM)

Dr. Iulia is a certified veterinarian with more than 10 years of experience in the field. With extensive knowledge of diet, care, and medication, she helps Misfit Animals provide readers with accurate knowledge on technical topics.

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