Feline Health - Fleas

This section gives some general information about some feline health problems.


The best peoples' cats have them!!

The problem with fleas

Since fleas can be carriers for worms and diseases, keeping your cat free of fleas helps to keep it healthy. In addition, many pets and people are allergic to flea-bites.

Has your cat them?

To check if your cat has fleas, part its hair and look for:

  • Small bits of brown "dust," attached to the fur itself. The fleas excrete digested blood. See if the dust dissolves into a red liquid upon contact with a wet paper towel.
  • Skin Irritation: flea bites or scratching and biting may leave red, irritated skin, and even bald patches in bad cases.
  • Small, fast moving brown shapes are fleas.

There are different varieties of fleas. The cat flea is common and the best people sometimes have them. This flee, not as well studied as the rat flea, spends all of its adult life on the host under normal conditions. Eggs are laid on the host and drop off into the environment. Eggs are often on bedding and throughout the house.

Finding a solution.

There are several ways to kill or discourage fleas. Some are synthetic chemicals, some are considered "natural", and both work with varying degrees. No one method is 100% effective, and a combination of several approaches may be necessary. Some methods are applicable for indoor cats, but useless for indoor/outdoor cats.

Finally, different methods may be required from year to year. Effectiveness is undoubtedly lessened if one product is continually used. Additionally, some years are worse than others, depending on the previous winter and again this may require a different strategy.


Recognising the 4-stage life cycle of the flea is important its eradication. From egg to larvae to adult is between three to six weeks: to get rid of fleas, this cycle must be broken. This almost certainly means repeated actions are necessary to ensure elimination of the fleas from the larvae that didn't get destroyed the first time around. This is also why it is important to address the problem of the eggs and larvae as well as the adult fleas.

After taking a blood meal, fleas either lay eggs on your cat or in its surrounding environment. Eggs on your cat are often shed onto its bedding or into the carpet. A pair of fleas may produce 20,000 fleas in 3 months. Eggs hatch after 2-12 days into larvae that feed in the environment -- generally on digested blood from adult fleas and other food matter in their environment. The food required at this stage is microscopic, and even clean carpets often offer plenty of food to the larvae. The larvae are about 3-4 millimetres long. Larvae moult twice within 2-200 days and the older larvae spin a cocoon in which they remain for between one week to one year. When in this cocoon stage the young flea is invulnerable to any kind of insecticide and to low, even freezing, temperatures. Only sufficient warmth and the presence of a host can cause them to emerge. This long cocoon period may explain why fleas are so difficult to eradicate. As a adult, they have been recorded as jumping over 6 feet.

So how to get rid of fleas.

Firstly in the house, sadly just treating you cat is not enough. Remember that carpets, rugs, and upholstered furniture are the prime places for depositing flea eggs. Having the carpets professionally cleaned WILL NOT get rid of the fleas, unless they use something that is meant to kill fleas. However, it will remove much of the eggs, larvae and the food that the larvae feeds on, so it can be useful in conjunction with other methods. You can spray the house. There are a number of commercial sprays that can be used. Generally, the house will have to vacated for a period of time. This can be effective; but it does depend on the chemical involved killing fleas, flea larvae, and/or both. The vet is a good source of information on effective brands.


For an immediate flea problem, bathing the cat with a flea-killing substance to get rid of the fleas on its body can be effective. But remember, the shampoo may sting when applied to open irritations and maybe the cat is used to being bathed- so this approach wants treating with care an caution.


Flea combs with fine teeth that snag fleas are available. Ammonia-laced water in a small dish can be used to kill the fleas on the comb rather than trying to crunch each one by hand. Alternatively, a few drops of detergent in a dish of water may be used so that there is no surface tension and fleas dropped into the treated water will drown. A metal comb is preferable as the plastic ones tend to be too flexible and allow the fleas to escape.

Most fleas will be found along the cat's back, groin area, and at the base of the tail.

Combing by itself will never rid the cat from fleas since flea larvae may also be in bedding, furniture and carpet. It is, however, a useful way to keep an eye on the flea population, and if used as a preventive measure can keep them in check. If you have a major infestation, though, you will have to get rid of most of the fleas before you can use just a comb on your pet.


Flea powders are handy, but there are many types and some are rather poisonous - many have been withdrawn from the market. When using powders, it is not enough to just powder the cat: powder its bedding, and under furniture cushions. It is important not to let the cat ingest flea powder of any sort.

Flea collars

Flea collars are generally reported not to be too effective and may even be bad for your pet's health. Some of the herbal ones smell nice and that's about it.

Ultrasonic and electronic flea collars are not known to work.

Flea sprays

There are several sprays on the market, in general the cat will NOT like what you are doing. So spraying can be potentially dangerous unless the cat is being held securely.

Systemic products

These products are probably the most effective and can only be obtained through a Vet.

Advantage (imidacloprid)

Advantage, (from Bayer), is an adult flea poison. It works by disrupting the flea's nervous system. It is a liquid that you apply to the cat's skin (on the back) and kills on contact (therefore fleas are not required to bite the cat). The substance will wash off. It is not absorbed into the bloodstream or internal organs. It is a repellant and an insectide, and people report cats being flea-free in a matter of days. Studies show that it is selectively toxic to insects as other animals have receptors that do not bind imidacloprid effectively and so are not affected. The product is effective for a month. Ingredients include: imidacloprid -- a chloronicotinyl nitroguanidine synthesized from the nitromethylene class of compounds. This binds the insect's nicotinyl receptor sites thus disrupting normal nerve transmission and causing its death.


Similar to Advantage, but is not water soluble (must use alcohol to wash it off). It can be used kittens and cats. It does not use pyrethrins/permethrins. It can repel for up to three months (in infested areas, the reported efficacy is closer to a month). Active ingredient is fipronil 5-amino -1- (2, 6-dichloro-4 [trifluoromethyl]phenyl) -4- (1,R,S)- (trifluoromethyl0sulfinyl) -1H-pryazole-3-carbonitrile 0.29% inert ingredients 99.71%. Fipronil is a nervous transmission interruptor, causing rapid death to fleas and ticks. Kills 96% of fleas in the first two hours, 100% within 24 hours. Ticks die before attachment. Fipronil is from the new phenylpyrazole class. Unlike any other molecule, fipronil acts on the GABA (gamma aminobutyric acid) mediated chloride channels of invertebrates. It is not systemic, it collects in the sebaceous glands (so you aren't supposed to give a bath 2 days prior or after, so there is oil on the skin for it to attach to). It has a toxicity rating of LD 50 which is similar to aspirin.

Program (lufenuron)

Ciba-Geigy Animal Health has pioneered an approach to flea control with the systemic use of an insect growth regulator (IGR), benzoyl phenyl urea lufenuron. This IGR acts as a chitin synthesis inhibitor causing mortality in hatching flea eggs and moulting larvae. Hatching fleas are unable to get out of the egg shell because the egg tooth, a chitin structure, cannot form. Larvae die during moults, again due to the inhibition of chitin formation. The IGR has no adulticidal activity, but female fleas that ingest the compound transfer it to the ovaries and eggs (transovarial effect).

Lufenuron, marketed under the PROGRAM tradename is available from the Vet only. It is administered orally with food in a suspension form. To maintain effective levels of control for a 30 day period, 30mg of lufenuron per kg of body weight is recommended. Dosages are absorbed from the intestinal tract into the general circulation and retained in adipose tissues. Excess is excreted. From the adipose tissue, lufenuron is slowly released back into the general circulation and excreted over time. The major route of elimination is via the faeces. Acute, sub chronic, and chronic dose studies revealed no adverse affects relative to the animals safety and tolerability. Used in conjunction with flea adulticides, no enhanced signs of toxicity were evident. It's also approved for use with nursing mothers. This is not toxic to adult fleas. Program has no warnings or contraindications it can be used in conjunction with other flea control products. The main drawbacks of this regime is that it is a preventive type of remedy; it will not work well (or immediately) against an acute flea population. It also requires that the cat be bit by all the fleas in the house for them to produce the defective larvae; this is not acceptable when the cat in question has flea allergies! Finally, for Program to be effective, all animals in the house need to be placed on it.

ALWAYS seek the advise of your veterinarian