Fleas in dogs and cats: how to spot, eliminate and prevent them

Fleas are among the most common parasites in dogs and cats. Contrary to popular belief, they don't only affect animals that live outdoors. A cat that never goes out or a dog that lives mainly indoors can perfectly well become infested.

A flea infestation can quickly become very uncomfortable for your companion and, if left untreated, spread into your home as well.

What is a flea?

Fleas are small parasitic insects, dark brown to black, about 2 to 3 mm long. They feed on animals' blood by biting.

Very agile, they can jump several tens of centimeters, which lets them move easily from one animal to another or around the environment.

A single flea can lay several dozen eggs a day. That is why an infestation can become significant in just a few weeks.

How does a dog or cat catch fleas?

Contrary to what people often think, direct contact with another animal isn't necessary.

Your companion can pick up fleas:

• on a walk;
• in a garden;
• through contact with another animal;
• in the common areas of an apartment building;
• at friends' or relatives' homes;
• in a boarding facility or shelter.

As eggs and larvae are present in the environment, sometimes a single flea jumping onto your pet is enough for the cycle to start again.

What are the symptoms?

Not all animals react in the same way.

The most common signs are:

• intense itching;
• frequent scratching;
• nibbling at the back or the base of the tail;
• excessive licking;
• hair loss;
• reddened skin;
• small scabs.

In some animals, just a few bites are enough to trigger an allergy called flea allergy dermatitis (FAD). The itching then becomes very intense and often requires veterinary treatment.

How can I tell if my pet has fleas?

Fleas aren't always easy to see.

You can, however, look for:

• adult fleas moving quickly through the coat;
• small black specks known as "flea dirt".

To check, place these specks on a damp paper towel. If they turn reddish-brown, it is indeed blood digested by fleas.

Health risks

A heavy infestation can lead to:

• severe skin irritation;
• allergic dermatitis;
• skin infections caused by scratching;
• anemia in young animals or in cases of massive infestation.

Fleas can also transmit certain parasites, in particular the tapeworm (Dipylidium caninum). An animal with fleas may therefore also need to be dewormed.

Treating your pet

Several options are available:

• spot-on treatments;
• tablets;
• antiparasitic collars;
• sprays.

The choice depends on the animal's age, lifestyle, state of health and the other animals living in the home.

Your vet can advise you on the most suitable treatment.

Warning: some products intended for dogs are toxic to cats. Never use an antiparasitic product without checking that it is suitable for your animal.

Treat your home too

This is an essential step.

Only about 5% of fleas are on your pet. The remaining 95% are in your environment, in the form of eggs, larvae and cocoons.

To prevent re-infestation:

• vacuum carefully over carpets, sofas, armchairs and baseboards;
• wash blankets and cushions at 60 °C (140 °F) whenever possible;
• empty the vacuum bag or dust container immediately;
• use an environmental treatment if necessary, following the manufacturer's or your vet's recommendations.

How to prevent fleas

Prevention remains the best protection.

Following your vet's recommendations, regularly use an antiparasitic treatment suited to your pet, especially during the highest-risk periods.

Also remember to check the coat regularly, especially after walks or time outdoors.

When should you see a vet?

Make an appointment if:

• your pet is scratching intensely;
• lesions appear on the skin;
• it is losing a lot of hair;
• treatments don't seem to be working;
• you suspect a flea bite allergy.

Key points

Fleas are very common and are not a sign of poor hygiene. A single flea can quickly lead to a major infestation if it isn't dealt with.

To get rid of them effectively, it is essential to treat both the animal and its environment.

Good to know

If you still see fleas a few days after treating your pet, it doesn't necessarily mean the treatment isn't working. Young fleas in the environment can keep hatching for several weeks before being killed on contact with the treated animal. It is therefore essential to keep cleaning the house and to respect the treatment's duration of action.

Read also

Fleas can transmit certain intestinal parasites, in particular the tapeworm. To learn more about the different worms in dogs and cats, their symptoms and how to prevent them, see also our guide Worms in dogs and cats.