Pet Factsheets

All about fleas

Fleas are the most common parasite in cats - and every cat is likely to be infected at some stage in its life. However, with the advent of modern products it is possible to prevent fleas from becoming a problem in your household. Working closely with your vet, who will you give you advice on how to use these products effectively, you will be able to stop these nasty little insects making a meal of your pet and you!

Why is it so difficult to get rid of fleas?

Fleas are small, reddish-brown insects with a complex life cycle, most of which takes place away from your pet. Only the adult fleas live on your cat and drink its blood, the early stages live free in the environment, ie, your home. For every flea that you see running through your pet's fur, there may be hundreds of immature fleas waiting to jump aboard a passing pet - or if you are unlucky - on to you.

Where do fleas live?

Adult fleas lay eggs in pet's fur. Each female flea can produce dozens of eggs every day. They are pearly white in colour and about the size of a grain of salt. The eggs do not stick to the fur and soon fall off on to the floor.

After a few days, the eggs hatch into maggot-like larvae which hide in your carpets, in cracks in the floor or in your cat's bedding. They feed on dust and the droppings of adult fleas, which mostly consists of undigested blood.

After a time the larva spins a cocoon in which it develops into an adult flea. They may stay in this resting stage for several months but finally the adult flea breaks out of its cocoon and crawls out of its hiding place to look for food. If it can not find a cat it will hop on to any warm blooded animal that passes by, including humans. Centrally heated homes provide ideal conditions for a flea to grow from an egg to an adult. The minimum time for the cycle is two and a half to three weeks but immature fleas can live for over a year before reaching maturity and reinfesting your pet. Most adult fleas live for 2-3 months feeding - the females feed on blood from biting your pet.

How do fleas damage my pet's health?

Fleas are the most common cause of skin disease in cats and dogs. Flea spit contains chemicals which stop blood clotting until the flea has finished feeding and these chemicals may cause an allergic reaction in your cat. Most animals are not affected by this allergy, but those which are, suffer severe itching. Affected animal lick or rub themselves, wearing away their fur and making their skin become red and sore. Sometimes a crusty rash will develop. Allergies appear most often in summer when the flea population is greatest. Skin problems may continue long after the flea which caused it has gone but they should eventually disappear if you treat your pet to remove fleas and continue treatment to stop fleas returning. In the short term your vet may prescribe some drugs to stop the itchiness.

Do fleas just cause skin problems?

Immature fleas pick up infection from the environment and may carry the immature form of tapeworms. If the flea is accidentally swallowed by an animal whilst grooming the tapeworm can develop inside the dog or cat's gut. Once inside your pet the tapeworm continues to grow and may reach as musch as 60 cm long. If you have seen fleas on your pet you should treat your pet with a product to remove tapeworms as well as getting on top of flea control.

How can I tell if my pet has fleas?

  • Take a sheet of good quality white paper and wet one side by running it under the tap.
  • Place the sheet on a flat surface, eg worktop with the wet surface uppermost.
  • Sit your cat against the edge of the paper.
  • Rub or brush the small of your pet's back so that scurf and flea droppings falls onto the wet paper or use a flea comb to brush your cat's coat and place the combings on the paper.
  • Look for 'coal dust' which, after 30-60 seconds, goes reddish brown (this is the dried blood in the flea droppings).

Sometimes there are no obvious signs of fleas and your vet might suggest testing your pet's skin to see if it is allergic to flea spit.

How can I get rid of fleas?

The secret of successful flea control is to treat both your pet and its environment with effective products which kill the adult and the immature fleas. There are a range of tablets, injections, powders, sprays, drops and shampoos to destroy the fleas in your pet's fur. Not all products are equally effective and those you can get from your veterinary surgeon are usually much better than those sold in pet shops or supermarkets. Other treatments can be given to your cat by injection to prevent fleas breeding in your house.

What is environmental flea control?

Treating the areas where your pet spends most of its time (including outhouses and sheds) is also important - particularly the places it lies down to sleep. Washing your pet's bedding in hot water will destroy the young fleas (but not the eggs) and vacuuming your carpets also helps keep the numbers down. Some products kill the flea itself and some prevent immature fleas from developing and reinfecting your cat in the future. Your vet can advise you on which product, or combination of products, to use. You must continue to treat your pet and your home all year round even if you do not see fleas.

What if I have other pets?

All the cats and dogs (because most fleas on dogs are cat fleas) in a household should be treated even if only one animal appears to be affected by flea bites. If you do not continue treatment the affected animal may be reinfected with fleas carried by other animals in your home or by fleas it picks up outside.


Fleas can be a real menace in centrally heated homes, particularly if you have more than one pet. Regular treatment with the products recommended by your vet should keep fleas under control all year round. Use your diary or calendar to note down when the next flea treatment is due - do not rely on your memory.