Fleas and Flea Control
September, 1996
In last month's article, I discussed the life cycle of the flea and some of the problems caused by the tiny pest. I mentioned that successful treatment of a flea problem should affect more than one stage of the life cycle. This usually involves treatment of outdoor and indoor areas and all other pets in the dog's environment. Last month's article also discussed treatment of the external environment. If the dog is allowed in the house at all, that area must be treated as well.
The house is frequently the most difficult treatment in the control process. All areas visited by pets must be treated. Carpeting and upholstery provide an ideal environment for the requirements of the flea larvae. To save the expense of a professional exterminator, most pet owners prefer to treat the house themselves. Thorough cleaning is important. Vacuuming with a powerful machine can remove many of the pre-adult stages. Afterward, application of a pesticide is still indicated.
Pesticides can be applied either in the form of a fogger or a hand-operated spray. Foggers, or bombs, have the disadvantages of being more expensive and inconvenient to use and they can miss vital spots, such as corners, closets and under furniture. Foggers can be used effectively by using one can per room and following their use with treatment of the trouble spots with a hand-operated spray. Most products contain an insecticide to kill the adult flea, but the most effective ones will also contain an insect growth regulator, or IGR, which prevents the larvae from reaching the pupa stage. The common IGR's are methoprene (Precor) and fenoxycarb. They are relatively non-toxic and can last for months. Because no treatment will effect the pupa in its protective cocoon, new fleas will be emerging from a properly treated house for weeks. Therefore, re-treatment in 2 - 3 weeks is recommended.
Health and environmental concerns have led to the use of various non-traditional pesticides. Of these, the most effective is sodium borate powder, or boric acid. The professionally applied product is guarenteed for one year. Flea traps, which stimulate emergence of the adult flea with warmth and vibration, can be effective. Environmental ultrasonic devices are apparently of no use.
There are many different products sold for treating fleas on the dog itself, but none is 100 percent effective in killing or repelling fleas. The key to successfully minimizing the number of flea bites that occur is correct and regular use of the chosen tool, or combination of tools.
Flea shampoos can effectively kill fleas on the animal's body, but they have no residual activity. That is, they are no use once the bath is over. New fleas can hop on the dog immediatley. Insecticidal collars are of limited usefulness. They kill fleas (or eggs) that are in close proximity to the collar, but do not protect the entire dog.
Flea spray, powder and dips (rinses) all have residual activity and can be applied periodically in an attempt to achieve continual protection from fleas. Most sprays have an alcohol base, which can be irritating to skin that is raw or injured from excessive scratching, but the alcohol tends to kill the fleas faster than any insecticide. Repeated application of sprays, powders or dips can dry the skin and dull the coat. Flea foam, or mousse, can have less drying effect on the skin and is easier to apply on those individuals that resent the sound and the feel of the flea spray. All of the topically applied flea products, just mentioned, may contain any number of chemicals, but the safest, and yet effective, class of insecticides is pyrethrins, either natural or synthetic (permethrin, allethrin).
Systemic products are those that get into the dog's bloodstream and affect the flea when it feeds on the dog's blood. Until last year two products in this category were fairly widely used - Proban (Miles Lab.), which is an oral pill, and Prospot, which is applied to the skin and absorbed. Both of these had the potential to cause side effects in otherwise healthy dogs, such as poor appetite, vomiting and diarrhea. Use of both of these products has decreased since a new, monthly, flea pill Program (Ciba-Geigy) was introduced last year. Program contains lufenuron, which appears to be non-toxic to mammals, but renders adult fleas unable to produce viable eggs. Although Program pills can very effectively eliminate infestation of the animal's environment, adult fleas that are rendered sterile can continue living on, and biting the dog or cat for weeks. All topical products can safely be used on an animal that is taking Program once a month, to help alleviate this disadvantage.
The final type of flea product I will discuss are those that are applied to one location of the body and are meant to spread throughout the skin, without getting absorbed into the bloodstream, so that a flea that bites anywhere on the body ingests the poison. The common product in the past years has been Defend Exspot (Coopers) which contains Permethrin. However, its intradermal spread to areas distant from its application, such as lower limbs, was shown to be ineffective. A new product, Advantage (Bayer) has only been on the market a few months. It contains imidacloprid, which kills adult fleas by interfering with their nervous system function. Like Program, it is only administered once a month. Preliminary test results show that it has adequate intradermal spread to all parts of the body, is still over 99 percent effective one month after administration and apparently has little or no side effects. One disadvantage is that its duration of activity is decreased when the dog gets thoroughly wet, so that those individuals that swim a lot or get caught in the rain would be left unprotected.
In conclusion, there are many options available for preventing and treating flea problems in dogs and cats. If convenience is the main factor, Program and Advantage are considered effective and are easy to use. They can also be used together, but this can get fairly expensive, especially for households with multiple pets. If cost is the main factor, frequent spraying can cut down on the flea population significantly. The tools you use in your flea control program depend on your own preferences and circumstances.