White dog in a field
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How do dogs get fleas?

By Nick Whittle Author

Updated on the

To be infested with fleas is horrible for your dog. Learn what you can do to treat and prevent fleas.

Dog fleas cause her to itch constantly and uncontrollably, and they may even damage her health: a bad bout of flea bites can take its toll of her, leaving her anaemic and prone to nasty infections. Young dogs and dogs that are already sick have even been known to die from excessive bites.

What is a flea?

A flea is a flightless insect closely related to flies, butterflies and moths. It is also known as a ‘parasite’ because it stays alive by drinking the blood of a larger animal. The adult flea measures about 3 mm in length and is reddish-brown in colour; it has a flat body which enables it to move easily through an animal’s fur.

Fleas have strong claws which they use to cling on to their host, and their tough bodies make them very difficult to dislodge by scratching. A serious flea infestation can cause a host animal to become incredibly frustrated and stressed.

Flea bites can remain inflamed for several weeks, and given the right conditions adult fleas can live for up to a year and a half.

Fleas also possess sharp mouth parts in order to pierce skin and suck blood. Once they have punctured a host’s skin, four pear-shaped salivary glands connected to the mouth by a special channel excrete droplets of saliva.

As a flea drinks the blood its saliva is dropped onto the area around the wound. According to research carried out by veterinary clinician V. J. Scheidt, some animals can have severe reactions to the bugs and chemicals contained within a flea’s saliva.

Scratching flea bites won't get rid of the parasite. ©Pixabay

Why do fleas like jumping on dogs?

Fleas (and ticks) choose a variety of warm-blooded vertebrates to be their hosts. Humans, dogs, cats, rabbits, squirrels, rats and birds are all targeted by the common flea. Although fleas prefer to feed from one type of animal they will often choose their next host because of its physical similarities with the previous one.

If you think your dog has been bitten by fleas you should examine the skin beneath her fur. Flea bites will cause a spot to form that is slightly raised, red and swollen; the spot has a single puncture wound in its middle similar to one caused by a mosquito bite.

In addition to a spot, you may notice the skin around it to be itchy and eczematous. Flea bites are usually observed in clusters or in lines of bites.

How does a flea hitch a lift on a dog?

Fleas don’t have wings. Instead they have specially adapted legs for jumping long distances; they are known to jump up to 50 times the length of their bodies. Such a mechanical advantage makes it very easy for them to cross from one animal to another and do so relatively unseen.

How do dogs get fleas? A dog’s social habit suits the flea’s life cycle. Her close contact with other animals will put her at risk of becoming a host. Dogs can attract fleas from other household pets as well as feral animals; the common mouse is a carrier of fleas and if you look after mice in your house your dog’s fur is prone to be infested.

Fleas can easily survive outdoors if the weather is warm and humid, although they prefer to nest in cool and shady areas.

If there are fleas on my dog what should I do?

You will know when your dog has fleas. She will be restless, she will scratch incessantly and she will bite her fur. An examination of the skin beneath her fur will reveal bites and traces of droppings and you may even notice small bites around your own ankles and calves. If you have been bitten you can treat the bites in the same way you would a mosquito bite.

At pet stores and vets’ surgeries you will find numerous formulae designed to treat and prevent canine flea infestations.

One of the first things you should do is bathe your dog in a pesticide-based shampoo. Once you have dried her, run a comb through her fur to see if you can see any fleas. If necessary repeat the process.

If you have been bitten you may have to accept the fact that there are fleas in your house. If you intend to treat the problem yourself, it is important you find a formula that will not endanger the health of other people or animals in the house (the ingredients of household treatments can vary).

Sofas, carpets, cushions, pillows and bedding should be washed or cleaned thoroughly, and due to the nature of the fleas’ mobility you should also clean and treat outside areas and car upholstery.

Make sure your dog is treated regularly against fleas.©Pixabay


In order to prevent further infestations ask your vet to treat your dog with a flea medicine and try to keep the house as clean as possible. The best way to prevent a flea infestation is to regularly use good quality flea control medicines and formulae recommended by your vet.

Should the infestation reoccur or be too great to deal with by applying domestic products you may need to hire an exterminator to fumigate the house.

Be especially vigilant in future when you are walking your dog or meeting other dogs. Avoid walking close to small bushes and through long grass, and keep all contact with wildlife (alive or dead) to an absolute minimum.

Checking her fur regularly is also a worthwhile thing to do; spotting flea bites early gives you time to act and is the difference between an unhealthy infestation and a small, manageable outbreak.

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