My dog always seems to be picking up fleas. What can I do?

Successful flea control involves:

1. Eliminating fleas from your dog
2. Controlling fleas in the environment

Fleas are not host specific. Dogs and cats share the same fleas so that it is important that all the pets in the home are treated with appropriate medication. Treatment of the pet is relatively simple since it is only the adult flea that has to be eliminated. When it comes to environmental control other stages of the life cycle have to be considered.

Do fleas have a complicated life cycle?

There are four stages in the life cycle of the flea and the adult constitutes only about 5% of the entire flea population, if one includes the immature forms.

1. Flea eggs are whitish and about half a millimetre (1/32 in) in length. They are very unlikely to be seen without a magnifying glass. The adult flea has to bite the dog for the essential blood meal. This is required for food and to complete the life cycle. Eggs are then laid on the dog but soon drop off on to the ground. They constitute approximately 50% of the flea population. High humidity and temperature favour rapid hatching.

2. Flea larvae are about 2-5 mm (1/8 to ¼ in) in length. They feed on organic debris found in their environment and on adult flea faeces which are essential for successful development. They dislike strong light and actively move deep into carpet fibres or under organic debris, grass, branches, leaves, soil etc. If outdoors they will develop outside if temperature and humidity are sufficiently high. Moisture is essential for survival and in many parts of the United States where outdoor temperatures are sufficiently high to stimulate development, humidity is too low and they are killed by drying. Outdoor larval development occurs only in shaded, moist areas where flea infested pets spend a significant amount of time so that adult flea faeces are available. Thus outdoor development of fleas in the United Kingdom is of far less significance than in southern Europe or the southern e US. In Britain our centrally heated, wall to wall carpeted homes afford an ideal environment for survival.

3. The pupae produces a silk like cocoon which is sticky. It quickly becomes coated with grime which acts as a useful camouflage. Again with warmth and sufficient humidity pupae become adult fleas in 5-10 days. The adults do not emerge from the cocoon unless stimulated by physical pressure, carbon dioxide or heat, i.e. the presence of a potential host. This is important since once emerged from the cocoon adults can only exist for a few days unless they are able to feed. Pre-emerged adult fleas within the cocoon will routinely survive 3-4 months and up to 9 months has been recorded. During this time they are resistant to insecticides applied to the environment. This is important because remember adult fleas may therefore emerge into the environment a considerable time after the application of any insecticides in the home.

4. Once emerged the adult flea, unlike the larvae, is attracted to light and therefore emerges to the surface of the ground cover (carpets etc) in order to encounter a passing host. Once this has been achieved the flea attempts to remain upon the host if at all possible but some dogs are particularly good groomers and the life span of the flea can then be very short. Two days after the first blood meal female fleas begin egg production. In normal circumstances the adult female will live up to three weeks, laying approximately 40 eggs per day. The entire life cycle, adult flea to à egg à larvae à adults can be completed in 14-21 days with optimum temperature and humidity.

Apart from irritation, are the fleas particularly harmful?

If there is a high infestation, particularly in a young animal, anaemia can occur due to the amount of blood being taken from the dog. A single female flea can take up to 15 times her body weight in blood over the several weeks of her adult life. In addition fleas can carry certain diseases and also act as vectors to spread one of the most common tapeworms of the dog and cat, Diplylidium caninum.

How do I prevent fleas on my dog?

As mentioned at the outset, successful flea control includes the environment as well as your pet.

What shall I put on my dog?

Shampoos, sprays, powders and spot-on preparations are all available, some on sale over-the-counter. Many however have no residual action and therefore if the environment is heavily contaminated fleas will soon reappear on your pet. Therefore it is worthwhile consulting us regarding specific advice in relation to particular circumstances. Oral preparations are also available which are absorbed by the flea on biting the dog. Other products also prevent completion of the life cycle, thus effectively curtailing flea population.

What about the environment?

Environmental preparations for use in the home are becoming increasingly sophisticated. It must be remembered that few preparations available at the moment are effective against any but the emerged adult flea. However if there is a prolonged residual effect although pre-emerged fleas are protected within the cocoon, if they emerge during the effective period after application of a prolonged action product they will be killed. In addition pre-emerged fleas can be encouraged to emerge by increasing the humidity and temperature before spraying the room.

How? Boil a kettle and turn up the central heating.

My dog lives most of his life outside. Obviously I cannot spray the entire garden, what shall I do?

Some products not only kill adult fleas but also contain growth regulators that prevent flea maturation. These are useful to use on the dog’s immediate environment, e.g. your home and any outbuildings in which he normally sleeps. In the occasional hot British summer and generally in southern Europe and the southern United States many dogs will live outside in summer months and in consequence will attract fleas from the outdoor environment which are ideal for rapid completion of the life cycle. Under these circumstances an effective preparation is required for regular use on the animal which has a high knock down effect, in other words kills any fleas on your dog very rapidly and also has as long a residual action as possible.

Some of the newer spot-on preparations available from veterinarians fulfil these requirements but if your dog does have flea allergy dermatitis, remember that in order to ingest the parasiticide the flea still has to bite the dog. This could potentiate the skin problem. This is but one reason for suggesting contact with your veterinarian in order to receive expert advice regarding flea control.

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