Fleas in Cats: Everything You Need to Know

Fleas are brown, wingless blood-sucking insects with a size of 2-6 mm. They have strong legs that make them very mobile and they easily jump between different animal species. There are a variety of race species, in fact several thousand.

The ones that cat owners usually come across are hedgehog fleas, rat fleas and bird fleas. These fleas thrive best on their own host animals but can cause temporary discomfort to both other animals and humans through their bites.

The cat flea

In the southern parts of Sweden for example, cat fleas (Ctenocephalides felis) are a common problem. The adult cat flea sucks blood and then lays eggs. The eggs are white, oval and about 0.5 mm long. A female lives 2-3 weeks and usually lays 15-20 eggs a day during her lifetime.

The eggs fall off in the environment where they then hatch into larvae. The larvae hide in the environment in, for example, floor cracks and carpets where they then undergo various stages of development. At the end of the caterpillar phase, the caterpillar spins a cocoon and a new flea comes out of the cocoon.

In most cases, the life cycle takes 3-4 weeks, but can vary depending on ambient temperature and humidity. In extreme cases, fleas can remain in their cocoons for several months before breaking out. In our indoor environment, the cat flea thrives excellently.


Flea saliva contains several irritating or allergenic substances and some cats develop allergies to cat flea bites. Globally, flea allergies are one of the most common causes of itching and skin problems. The skin changes with rash and hair loss are typically located on the back, buttocks, flanks, tail and the area around the anal opening.


It is important to find out which flea species has affected the cat. The fleas are determined under a microscope. The fleas differ through different head shapes and through the combs (ctenidia) that are on the head and / or front body. The treatment strategy depends on the type of flea the cat has.

If the pet owner suspects that the cat has been affected by fleas, a lice comb can be used to try to find them. It is also possible to see feces from the fleas. The stools are seen as dark dots. If a little water is dropped on such a dot, it dissolves and turns brownish red from the blood that the flea has sucked.


If the cat has received hedgehog fleas, rat fleas or bird fleas, they often disappear on their own. Some antiparasitic agent may be used as treatment. In the case of cat fleas, the cat is treated with an antiparasitic agent that makes it difficult to hatch new eggs. The tablet is given every month for 6 months.

The most important thing is to clean up the environment as the amount of eggs, larvae and pupae far exceeds the number of fleas on the cat. Environmental remediation can be difficult, and it can be a good idea to hire a pest decontaminator. It is also important to think about treating all animals that the cat has daily contact with, for example if there are several cats or other animals in the home, everyone should go through treatment.

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