The Classic Comprehensive Handbook of Cat Care: FLEAS
Fleas are probably the most prevalent external parasite of cats. Fleas are wingless, small dark brown insects capable of jumping great distances relative to their body size. They obtain nourishment by sucking blood.
Fleas are not very host-specific. In spite of the fact that there are several flea species, cat fleas (Ctenocephalides felis) can be found on dogs, dog fleas (Ctenocephalides canis) can be found on cats, and cat and dog fleas will feed on humans. Human fleas (Pulex irritans) also feed on dogs and occasionally on cats. The important thing is not the kind of flea present, but that a cat should not have fleas at all. A single flea on a pet is a cause for concern. Flea infestation should not be considered a normal or natural condition, and just a few fleas can sometimes be responsible for significant loss of blood in kittens, old animals, or any weakened cat. This blood loss (anemia) can result in death, particularly in young cats. Fleas are carriers of disease, including the organism that causes human bubonic plague and also tapeworms. Allergic dermatitis is also commonly caused by fleas.
ADULT FLEA FEEDING ON CAT
FLEA LIFE CYCLE—IMPORTANT IN CONTROL
Female fleas lay their eggs only after consuming a blood meal. They may lay them directly on the host, but because the eggs aren’t sticky, they usually drop off. Flea eggs are white and about the size of a small grain of salt. If a cat is heavily infested with fleas, eggs may be found in his or her coat mixed with flea feces (partially digested blood), which are about the same size but colored black. (Moistening suspected flea excreta should produce a blood red spot.) The eggs hatch into larvae anytime from two days to two weeks after being laid. Mature flea larvae resemble very small fly maggots. They are about one-quarter (about 6 mm) inch long and white to creamy yellow in color. They are usually found in cracks in floors, under carpets, in pet bedding, and other similar places. The larvae feed only a little, eating adult flea excreta or other organic debris in the environment.
Then they spin cocoons in which they develop into adult fleas. Depending on environmental conditions, larvae may take from about ten days to several months to become adult fleas. They are very sensitive to drying; therefore, they prefer an environment that is uniformly moist but not wet, a condition that is often found in sandy areas outdoors. Once larval fleas enter their cocoons, they are called pupae. Pupae are extremely resistant to any chemical or physical means of destruction and may survive for up to twenty months before emerging as adult fleas. After hatching, adult fleas can live up to twelve months without feeding, just waiting to jump on your pet.
Since a major part of the flea life cycle takes place off the cat, flea control on a single host is not sufficient to get rid of fleas completely.
Fastidious housekeeping is essential, and flea control must be practiced on all pets living in a single house. Existing fleas must be removed from the premises (including from vehicles in which fleainfested pets have been transported) so that the pet can be used as a sentinel to alert you to any potential reinfestations.
Washing or burning infested bedding and thorough vacuuming can be sufficient to get rid of small numbers of fleas providing the cleaning routine is kept up weekly year-round and providing that all pets in the household are kept scrupulously clean. In the case of a moderate to heavy infestation, houses, yards, and catteries must be sprayed or fumigated with commercial insecticides, or the services of professional exterminators must be obtained.
HOW TO DETECT FLEAS AT HOME
Two ways to detect fleas in your environment are the white handkerchief and white sock techniques. In the first, a white linen handkerchief is inserted between the end of the vacuum cleaner hose and its coupling to the power source. After vacuuming the pet’s sleeping area, the carpet, and other areas (even the cat), remove the handkerchief and place it quickly and carefully into a plastic bag. Then seal it. With a magnifying glass, it is easy to detect flea eggs, larvae, pupae, and even
adult fleas trapped in the handkerchief.
The white sock technique detects adult fleas in a suspected area. Put on a pair of white knee socks and walk briskly around the suspected area for five minutes. Fleas respond to vibrations in the environment, body heat, and exhaled carbon dioxide and often jump onto the socks, where they can be seen. Any flea observed is significant, as one adult female flea can lay up to forty eggs per day and a breeding pair of fleas can easily produce 600 offspring in a month!
HOW TO SELECT FLEA CONTROL PRODUCTS
Products for treating premises that have fleas include insecticides, insect growth regulators, and a few noninsecticidal products. Insecticides are available as liquids to be sprayed in- or outdoors or as indoor foggers (“bombs”) that release a fine mist into the air when activated. Any good veterinary clinic should be able to help you select a product, but be sure to read the labels on any products you choose and ask any questions that may come to mind. It is very important to select insecticidal products that have the lowest possible toxicity to species other than the flea and that are nonpersistent in the environment (see chart). Most products that meet these requirements need repeated application to the infested area (usually every two weeks for at least three or four applications) to eliminate adult fleas, which will continue to emerge from the pesticide-resistant cocoon stage as the previously applied pesticide degrades.
Insect growth regulators (e.g., methoprene, fenoxycarb) are biochemicals that mimic the insect hormone necessary for proper flea development, thus disrupting the early flea life stages and causing them to die. These products can provide about two to five months of persistent flea control when applied to areas harboring only flea eggs and larvae. They cannot kill pupae or adult fleas. Although these relatively environmentally safe chemicals cannot by themselves provide full flea control, they can lessen the amount of pesticide that has to be applied to the environment over time in order to kill adult fleas by eliminating fleas in the earlier life stages. Insect growth regulators are included in various premise sprays, foggers, and pet sprays in combination with a variety of insecticides.
Nematodes that disrupt the flea life cycle by killing flea larvae and pupae are contained in some other products used for premise flea control. Read the labels and, if necessary, ask your veterinarian for advice on how to find the best product for your circumstances, as more than 300 products are available for the control of fleas on pets and premises.
Nonchemical methods of flea control are important to the success of any program using chemicals and for continuing good flea control once fleas are eliminated from the premises. Before using flea-control products, thorough cleaning of washable floor surfaces and vacuuming of carpets (a vacuum equipped with a beater bar is best) and furniture is critical. Special attention should be given to baseboards, sheltered areas under furniture, and the spaces around and under furniture cushions. Burn the vacuum cleaner bags after use.
Pieces of flea collars, or flea powders placed in vacuum cleaner bags will also kill emerging adult fleas. However, they may also result in additional aerosol environmental contamination by pesticides, and this is not an approved use of insecticides by the Environmental Protection Agency. Also avoid using napthalene moth crystals (moth balls) in vacuum cleaner bags to kill fleas since they can generate explosive gas. Area rugs should be washed regularly, and steam cleaning of wall-to-wall carpets will kill all flea life stages if done properly.
Various insecticides and larvacidal products can be applied in carpet- washing solutions if necessary, and drying products that kill fleas by desiccation can be sprinkled on carpets. The major key to good flea control is absolute cleanliness in the environment and on the pet.
START PET FLEA CONTROL WITH A BATH
If your cat has fleas, the first thing to do is to give him or her a good bath. You can use a gentle human shampoo or a commercial shampoo containing insecticides to kill fleas. If you use a regular shampoo, remember that you are only removing fleas mechanically. If you don’t rinse your cat’s coat well, fleas stunned by the water will wake up as the coat dries and still be around to cause trouble. Insecticidal shampoos have no significant residual action, but they do help kill fleas during the bath. A bath once a week followed by a cream rinse can be sufficient for flea control in low-flea-density areas. (Certain bath oils and cream rinses designed for people seem to have flearepelling effects. Ask your veterinarian for instructions for using a specific product on your cat.) Once your cat is clean, use any of the following for continued flea control.
Dips are insecticides that are applied to the cat’s coat as a liquid and allowed to dry. It is easiest to sponge on a dip while the cat is still wet following a bath. It is not necessary to immerse a cat in the dipping liquid.
Avoid applying insecticides around the cat’s eyes, nose, and mouth (even if directed to do so by the label). Dips containing pyrethrins or synthetic pyrethrins (see chart) are generally less toxic and less environmentally persistent than those containing other insecticides, and they can provide very effective flea control if applied regularly. Some dips contain insect growth regulators. In areas with a major flea problem, it is desirable to switch between product categories periodically to avoid the possible emergence of a strain of flea resistant to any single insecticide group.
FLEA SPRAYS, ROLL-ONS, AND POWDERS
Flea sprays, roll-ons, and powders (dust) are made from a large variety of insecticides, insecticide potentiators, and sometimes insect growth inhibitors in an alcohol or water carrier (sprays, roll-ons) or a diatomaceous earth or silica carrier (powders). In general, the same considerations about toxicity, environmental persistence, and flea resistance apply to the selection of a spray or powder as to a dip. You may want to ask your veterinarian what is currently recommended in your area.
In general, powders, sprays, and roll-ons must be applied frequently—often daily—to provide good flea control. Many animals and owners object to this process. It is important to apply most powders and sprays moderately and regularly, rather than infrequently and heavily, if good flea control is to be achieved. The legs, back, tail, and rump of the cat are the most important areas to cover, and it is essential to apply these products near the skin by pushing the hair against its direction of growth and rubbing the product in. It is often helpful to apply sprays or powders just before a pet is allowed outdoors. This allows any fleas that jump on during outdoor activity to be killed immediately (and not brought back indoors!), as well as allowing sprays to dry and excess powder to fall out of the fur.
Avoid applying sprays or powders to irritated or raw skin. Insecticides are more readily absorbed systemically from areas where the skin has been broken. Alcohol can be irritating to sensitive skin, and the drying action of the carriers in flea powders—which itself helps kill fleas—can also be irritating to both normal and abnormal skin.
Many flea collars contain organophosphate or carbamate insecticides incorporated into a plastic base that allows their slow release. These chemicals kill fleas directly. Their action in flea collars is not due to absorption by the cat and ingestion by the parasite with a blood meal.
Some collars contain insect growth regulators that prevent flea eggs laid on the pet from hatching. A false sense of security may arise when a pet wears a flea collar, and this can result in infested premises if early evidence of collar failure is not noticed. Collars should be replaced on a regular schedule well before the stated expiration date on the package.
Pets wearing flea collars should be bathed frequently and examined often for fleas. Any evidence of fleas on a pet who is wearing a flea collar is grounds for reevaluation of the full flea control program with special attention to the premises.
Flea collars can be used safely on healthy cats as young as two months of age, but package directions to the contrary should be heeded. Flea collars should be applied so they can move freely on the cat’s neck, and wetting should be avoided to prevent premature loss of the antiflea effect. Other insecticides should not be applied in the presence of a flea collar unless advised by a veterinarian.
FLEA COLLARS CAN CAUSE CONTACT DERMATITIS
A few cats are sensitive to insecticides and develop contact dermatitis when a flea collar is applied. The dermatitis often first appears as hair loss and reddening of the neck skin under the flea collar. If the collar is not removed, the skin condition can progress to large raw areas, sometimes secondarily infected with bacteria, that can be difficult to clear up and need the attention of a veterinarian. Flea collar dermatitis can sometimes be prevented by airing the collar for two or three days before putting it on the cat. Cats who cannot wear flea collars should not have similar insecticides applied to their skin in the form of dips, sprays, or powders.
MANUAL FLEA REMOVAL
Removal of fleas by hand or with a flea comb is an extremely inefficient method of flea control. To ensure a flea-free animal, the entire coat must be combed by hand for at least forty-five minutes daily, a process few people will routinely undertake. Of course, if you see a flea, you should remove it, but don’t rely on this as a means of routine control if other methods can be used. If they cannot be, be sure to combine combing with regular bathing and extremely fastidious housekeeping. And consider purchasing a flea-comb unit that can attach to your vacuum cleaner.
Suction increases the effectiveness of the combing process.
Scientific experiments have been unable to substantiate the effectiveness of home remedies against fleas, such as applying ultrasonic collars or eucalyptus bud- or pennyroyal oil-impregnated collars or feeding cats garlic or brewer’s yeast. Flea traps that consist of a light source suspended over sticky paper have been shown by scientific experiment to catch no more than 2% of fleas released into a controlled environment. If you want to stick to such remedies, examine your cat thoroughly and frequently for evidence of fleas. If any are present, immediately reevaluate your means of flea control.
SYSTEMIC FLEA CONTROL
Organophosphate insecticides have been developed that are designed to kill fleas only after they have taken a blood meal from a pet. These products were developed for dogs and can be extremely dangerous to cats. They have a potent ability to lower an animal’s blood level of cholinesterase, an enzyme that is important to normal nervous system function. They can result in significant drug interactions when other drugs with similar effects are administered in the course of anesthesia or disease treatment and are readily toxic themselves to cats, causing vomiting, muscle tremors, hyperexcitability, drooling, diarrhea, and death.
Common names of systemic flea control drugs are cythionate and fenthion. Avoid them in cats. Lufenuron, an orally administered insect growth regulator, prevents eggs from fleas that have fed on treated cats from hatching. Although it is a relatively safe drug, it cannot kill adult fleas and is best used only with a full understanding of your cat’s flea control needs.
The sticktight flea Echidnophaga gallinacea is mainly a parasite of poultry, but it can attack cats. You can recognize sticktight fleas easily because the adults stick tightly to the cat’s skin and don’t run off when approached. They are voracious blood suckers and, if found, should be removed by the use of a flea dip followed by routine means of environmental flea control.
CAT OWNERS CAN ELIMINATE FLEA INFESTATION
In the Middle Ages it was common for humans, dogs, and cats to be infested with fleas. Modern standards of cleanliness have made human infestation with fleas rare and unacceptable in normal, clean environments.
This state is maintained without antiflea dips, sprays, and powders as part of one’s daily toilette. A similar state exists for cats who are kept clean and who live in clean households surrounded by neighbors who set the same high standards for their pets. Flea infestation could be a thing of the past for pets if all cats and dogs had owners who gave them good care.