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Treatment and prevention of fleas in cats

 
, medical expert
Last reviewed: 04.07.2025
 
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The common cat flea (Ctenocephalides felis) is the most common parasite on cat skin. Any cat can become infected, except those living at high altitudes, as fleas do not live above 1,500 meters. Cats living indoors can have fleas all year round.

Fleas survive by jumping on the host animal, burrowing into its skin and feeding on blood. In most cases, they cause only mild itching, but in severe infestations, especially in kittens or older sick cats, they can cause severe anemia or even death. Fleas are also intermediate hosts for helminths. Some cats are hypersensitive to flea saliva. This causes severe itching and a local or general skin reaction.

A flea infestation can be identified by finding fleas on your cat or by seeing black and white specks in the fur that look like salt and pepper. These specks are flea feces (the "pepper") and flea eggs (the "salt"). The feces are made from digested blood. When combed out onto damp paper, they turn reddish-brown.

An adult flea is a small, dark-brown insect, about 2.5 millimetres in size, that can be seen with the naked eye. Although fleas have no wings and cannot fly, they have powerful hind legs that allow them to jump long distances. Fleas move quickly in fur and are difficult to catch.

Look for fleas on the cat's back and in the tail and back area. To do this, go over the fur with a fine-toothed comb. Sometimes fleas are visible in the groin area, where it is warm and there is less fur. Itching is most pronounced in these areas.

New methods of fighting fleas

New products such as Program, Advantage, and Frontline have virtually replaced the use of solutions, powders, sprays, and shampoos in flea treatment and prevention. The new products are more effective and safer than traditional insecticides. They are also easier to apply.

Program (trade name lufenuron) was the first and remains one of the most popular flea control products for cats. Program is a tablet or liquid given once a month with food. It is also available as an injection, given every six months.

The active ingredient accumulates in the cat's subcutaneous tissue and is effective when a flea bites the cat. Program inhibits the growth of eggs and the hatching of fleas. This results in a steady reduction in the number of new fleas in the environment. Its effect is limited to the hard outer shell of the flea, and the product is completely harmless to mammals. However, since the product does not work on adult fleas, it may take 30 to 60 days or more before the adult fleas die of age and you notice a reduction in itching and scratching. All animals in the household must be treated with Program for the treatment to be effective.

Advantage (imidacloprid) is a liquid topical medication that kills fleas on contact and is taken once a month.

After application, 98-100% of adult fleas are killed within 12 hours. This means that any new fleas that infest the cat must be killed before they have a chance to lay eggs. This breaks the flea life cycle and ultimately kills all fleas in the environment. Advantage is not metabolized by the cat and is therefore non-toxic. Humans do not absorb this chemical from contact with a treated cat. Advantage can be used on kittens from 8 weeks of age.

Frontline and Frontline Spray contain the active ingredient fipronil, which kills fleas on contact within 24 to 48 hours. The flea does not have to bite the cat for the product to work. Frontline is a topical liquid product in a tube, applied in the same way as Advantage.

Frontline Plus contains S-methoprene, which kills adult fleas, eggs, and larvae. It also treats for lice and is used as part of a treatment program for scabies. Frontline Plus is for kittens 8 weeks of age and older.

Revolution (selamectin), a heartworm preventative, is a topical liquid applied monthly to the skin of your cat's neck between the shoulder blades, like Advantage. It also treats adult fleas and prevents fleas from hatching from eggs. Selamectin can also be used to treat ear mites, roundworms, hookworms, and some ticks.

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