Fleas

Fleas

How do they enter the house?

Fleas can enter the home in many ways, even if your pet is not or only rarely allowed outside. They can hop in from your yard, hitch a ride on you, or even be left over from previous inhabitants (larvae can remain dormant for astonishingly long periods of time under a variety of conditions).

Why should I worry about fleas?

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

How can I tell if my pet has fleas?

To check if your pet 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.
• Or, use a flea comb and see what you get.

You may also see "flea dust," fleas, or even larvae on your pet's bedding.

Dried blood in its ears may indicate ear mites and you should consult your vet to find out what the problem is.

Preventive measures

Conventional wisdom and older studies that studied rat fleas suggest that fleas spend only part of their time on your pet; this is not true. There are different varieties of fleas, and the primary flea infesting dogs and cats in North America and large areas of Europeis the cat flea (yes on dogs, too). This flee, not as well studied as the rat flea actually spends all of its adult life on the host under normal conditions. Eggs are laid on the host and drop off into the environment. Thus you can often find eggs wherever your pets spend time: on their bedding, through the house, in the backyard.

A good preventive method is to put down towels everywhere your pet normally lies and then wash those towels once a week. Deposited flea eggs are therefore cleaned out regularly. Regular vacuuming and emptying of the vacuum bag also helps, independently of any method or methods you choose to do, since that eliminates or reduces food sources for the larvae.

How to choose your methods

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 you will almost always have to combine several approaches to get the results you want. Some methods are applicable for indoor pets, but useless for indoor/outdoor pets. You need to choose the set of approaches that best addresses your situation.

Keep in mind that there are regional differences among fleas: what works well in one area may not work well in other areas. You should consult a LOCAL vet, vet tech, or dog groomer to see what is known to be effective in your area. If you thinkyou're getting biased opinions, ask several people and see what they concur on. Don't rely on the products available at your local store; there are too many that are just distributed nationally.

Finally, you may find that you need to switch your approaches around from year to year. If you use the same product several years in a row, you may find the effectiveness lessened. Additionally, some years are worse than others, depending on the previous winter, and you may need to strike earlier with stronger methods some years and relax a bit more with milder methods another year.

Lifecycle

You must keep in mind the life cycle of the flea. From egg to larvae to adult is between three to six weeks: to get rid of fleas in your house, you must break this cycle. As a practical matter, this means you will almost certainly have to repeat your efforts in several weeks to catch 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 pet or in its surrounding environment. Eggs on your pet 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 little wiggles about 3-4 millimeters long, you may see some if you inspect your pet's bedding carefully. Larvae molt twice within 2-200 days and the older larvae spin a cocoon in which they remain for 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 cocooning period explains why fleas are so difficult to eradicate.

Keeping clean

Having your 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.

Remember that carpets, rugs, and upholstered furniture are the prime places for depositing flea eggs. Some people have success ridding their home of fleas by removing their carpets and replacing with linoleum or hardwood floors. This may not be a feasible option for everyone, though.

Natural methods

These tend to be of the "folk-remedy" type. Some people swear by them, others do not get any results. Some are actually toxic. They tend to work better at keeping fleas away rather than killing or eliminating present infestations.

• You can buy cedar shampoo, cedar oil and cedar-filled sleeping mats. Cedar repells many insects including fleas.
• Let outdoor pets sleep on a well-used horse blanket. Equine-l folks have confirmed that horses get ticks but not fleas, and cats using horseblankets in *current* use seem to have fewer fleas.
• Fleas love dry skin: prevent dry skin by giving your pet Linatone (or any vegetable oil) with its food and avoiding excessive shampooing.
• Pennyroyal (the herb and the oil) is often touted as a natural flea repellent: only the fresh or dried leafs are safe. The oil is actually highly toxic to animals and humans (it has a long history as an abortifacent, for example). There is an article about this in the AKC's Gazette, July 1992. Also, Journal of the AVMA, v200 n6 March 15, 1992.
• Garlic and Brewer's Yeast: Feed it in small doses to your pet and and the resultant body odor may repel fleas. You can get it either in powder form or tablet form, at varying expense.
• Orange or lemon peel boiled and simmered in water makes a flea dip after it cools. Do not use this on cats, however (don't know about ferrets). Rinse well.
• 60 ml of lavendar oil mixed with 2.8 liters of rock salt can be placed under furniture and rugs.
• Eucalyptus leaves can be left under furniture and rugs. Also, a eucalyptus wool wash [a product for washing wool made from eucalyptus, available in Australia, perhaps elsewhere too] when washing the dog may help.
• Rub bruised fennel foliage into the dog's coat. Growing it in the yard discourages the establishment of fleas there.
• You can plant marigolds outside in your garden. This has the additional benefit of repelling a variety of other bugs.
• NuPo offers a "flea trap" that uses heat to attract fleas to a sticky pad, kind of like "flea paper." Homemade variants, considerably less expensive, include leaving out detergent-laced dishes or jars of water near nightlights at night. This approach works best in severe infestations but is not likely to eliminate the fleas.
• Food supplements, there are several on the market besides the "conventional" brewers yeast and/or garlic. One is Hop Off. Again, they appear to work for some dogs and not necessarily others.
• Often useful in conjunction with other methods is to cover up your pet's ears and around the neck with a wet towel and have it lie in a tub of cool water for a while. The towel prevents migration of the fleas to the head. Add just a little detergent to the water (a teaspoon or a few cc's is enough) to make sure the fleas drown. Obviously, your pet must be amenable to lying in water for 15 minutes or so. This can be done as an alternative to dipping; but like dipping it will not solve the larger problem of the flea infestation.
• A similar method is to prepare a warm bath in the kitchen sink (or tub) with just a little baby shampoo and submerge the pet except for the head. Hold the vegetable sprayer (or spray attachment) about an inch away from your pet (under water) and literally blast the fleas off. By doing it under water, it keeps the fleas from simply being blown to another part of the pet. The head has to be sprayed while out of the water. Fleas will float to the surface but drown because of the bit of shampoo in the water. This may help remove eggs as well. Again, this technique only works on animals that are amenable to lying down in water.

Spraying inside

There are a number of companies that will spray your house and typically they have guarantees such as "flea free for a year" (or they will reapply free of charge). The best known one is probably FleaBuster. FleaBusters applies a product to your carpet that kills all the fleas and eggs. Many people report that the results last for longer than the guaranteed year. Other people have pointed out that the product FleaBusters uses is Terminator (see below), and applying it yourself can be a significant savings over what FleaBusters charges.

You can spray your house. There are a number of commercial foggers and other devices which you set off in your home. Generally, you and anything live will have to vacate for a period of time. This can be effective; it depends on if the chemicals involved will kill fleas, flea larvae, or both. Your vet will be a good source of information on effective brands, or you can have this done professionally.

Remember that a hand-held sprayer will be more effective than a fogger-type application simply because you can make sure all the hard-to-reach areas are properly treated.

In general, pyrethrins are "low intensity", relatively safe, and break down quickly (some on contact with sunlight). They can normally be used safely with puppies, kittens and in sensitive conditions. Pyrethrins are from chyrsanthemums, and manage to be highly toxic to fleas but not to people or dogs. It's very safe. Permethrins are synthetic pyrethrins and have the additional benefit of a residual effect for several days.

Organo-phosphates are "heavy duty" and last longer. They should be used with caution as they are usually toxic to people and animals.

The Insect growth regulators do not kill adult fleas, but they have little or no toxicity to non-insects as they very specifically target the flea larvae, preventing its transition to adult stage.

Precor: (methoprene)

This is an insect hormone that interrupts the life cycle of fleas by preventing flea larvae from maturing. It is not a poison, even to fleas, but they cannot reproduce. It's used as an environmental spray either by itself (in which case it will take several weeks to show much effect) or combined with adult pesticides (like pyrethrins) for a quick wipeout.

Because it's a hormone, it's thought that fleas can't become resistant to it. However, methoprene resistance has been reported in experimental population of fleas. If you're getting poor results with Precor (=methoprene), you might try Fenoxycarb.

You can buy the stuff at your local hardware/gardening store, and spray the diluted (according to directions) liquid everywhere in the house. This will not kill fleas by itself unless you combine it with something immediately lethal, but it will break the lifecycle and the fleas will go away in a few weeks as the mature ones die and the immature ones fail to develop. Such an application lasts about 4-5 months. Precor cannot be used outside because it breaks down rapidly in sunlight, but there are new formulations, such as Fenoxycarb, that show promise for outdoor use.

Precor is most often combined with other agents, like pyrmethrins. Currently available are powders, sprays, and foggers all containing the ingredient. It can be difficult to find a source of pure methoprene. One mail-order source is Gardens Alive! It's called Vigren and is $9.25 per oz concentrate (mix with 1 gallon of water, covers 1500 sq. ft) or $7.95 for three or more. Address below.

Torus:

This is a pure form of fenoxycarb, an IGR. It can be used outdoors since it doesn't react to UV like methoprene does. It is available through Kristull Products, 8708 Grelle Lane, Autin, TX 78744; 800-658-6699. Many products now contain fenoxycarb, but Torus seems to be the only undiluted form available. Due to company buyouts, Torus has been discontinued from the market, though there is still some stock available from distributors.

Archer:

This is a Torus like product against fleas (and fire ants). Check:

• http://www.fleasmart.com
• http://www.dawwn.com/flea/archer.htm
• http://www.fleas.kristull.com/

Sectrol:

This is microencapsulated pyrethrins (low toxicity to mammals). This works well in conjunction with methoprene. Spraying your home with this combination should be good for about 5-6 months before reapplication is needed. Use the Sectrol Pet and Household Flea Spray #1495 for the pure micro encapsulated pyrethrin product (3M has a variety of "sectrol" products). Expensive.

Duratrol:

This comes in both a spray (for the house) and a dip for the immediate problem on your pet. The smell is reported to be minimal and the effectiveness high. You only need to leave the house for 1/2 hour to allow the spray to dry (rather than up to four hours for other sprays and foggers, for example). Duratrol consists of micro- encapsulated chlorpyrifos -- essentially Dursban in "tiny time pills."

Foggers:

When choosing a fogger, note that the directions call for one can per X no. of UNOBSTRUCTED square feet. In practice, that means one can per major room. You can increase the effectiveness of the spread of the fogger by setting up fans to move the air around before you trigger the foggers. If you have a forced-air furnace, set the fan to on and thermostat to off (turning the thermostat off ensures that the heaters do not kick in; most fogging sprays are flammable or explosive). Foggers have a real problem in penetrating enough to do any good, though. They just don't reach under furniture and other inaccessible places.

Treating outdoors areas

When treating the area surrounding your house, remember that fleas are not found in your driveway gravel or in the open. The larvae do not survive high temperatures. They are found in shaded areas, like under porches, decks, car ports, at the edges of woods, and especially in places where your pets lay down outdoors.

Dursban:

You can use Dursban for ridding the yard of fleas. Home Depot will have the generic stuff. Spray according to the directions on the label. This is fairly toxic stuff. The generic name is Chlorpyrifos.

Nematodes:

This is a new product for outdoor treatment. "Bio Flea Halt" and "Interrupt" are two brand names -- probably others exist. Nematodes are bugs that eat fleas. You apply it to your backyard with a pump sprayer; hose sprayers will also work. [Not sure about details of application: do you apply to grass? dirt? what about decks? effect on existing plants?] Toxicity to humans/dogs is non-existent, early studies show a good degree of effectiveness.

For those with outdoor pets, diatomaceous earth, boric acid and silica aerogels can be used to treat your lawn for fleas and ticks. These chemicals were lauded by the Apr 92 Sunset magazine in their list of least toxic chemicals, sprays and dusts, which were discussed for those people who want to control pests more naturally. These are not poisons, and kill by clinging to, scratching and and destroying the waxy exteriors, or dessicating the pests. Sunset does point out that these chemicals should not be inhaled as they will irritate or abrade the lungs in the same way (which isn't a big problem once they've settled into your lawn). Diatomaceous earth is an abrading agent (much like borax). Use natural grade rather than pool grade diatomacious earth. Boric acid is also a abrading agent. Silica aerogels are dessicants, and kill the insects through dehydration. It is recommended that these chemicals be used in powder form to kill fleas and ticks.

Dipping your pet

For an immediate flea problem, you can bath your pet with a flea-killing substance to get rid of the fleas on its body. But remember, such "dips" usually sting when applied to open irritations. Animals have been known to bite, climb up your arm, and even urinate all over themselves, so be prepared!

Be very careful to only dip animals that are at least two, preferably three months old, and be especially careful to use appropriate dips. That is, do not use dips marked for dogs on cats!

Avon's Skin-So-Soft lotion is reputed to repel fleas (as well as mosquitos on human). After bathing your dog, put some lotion in the rinse water. They will smell like the lotion, and the application will last for a few weeks. This may be a problem for pets that groom themselves. Another way to apply it is to put a 1:1 lotion:water mix in a spritz bottle and mist your dog with it. Some people report excellent results and others do not.

Dipping alone will NOT solve the more general problem of the flea infestation.

Combing your pet

Flea combs with fine teeth that snag fleas are commercially available. It is helpful to have a small dish of ammonia-laced water on hand to kill the fleas on the comb rather than trying to nail each one by hand. Alternatively, mix a few drops of detergent into the dish of water so that there is no surface tension and fleas dropped into the treated water will drown. Use a metal comb; the plastic ones are too flexible and allow the fleas to escape.

You will typically find the most fleas along your pet's back, groin area, and at the base of the tail.

This by itself will never rid your pet 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.

Powders

Flea powders are handy, but there are many types and some are rather poisonous. Check the poisonous list below for ingredients that cause serious problems (for cats). When using powders, it is not enough to just powder your pet: powder its bedding, and under furniture cushions. You may want to add some to a discarded vacuum cleaner bag especially if it will sit in the trash for a few days, but don't run a vacuum with flea powder in the bag. That will probably spray it in the air, potentially toxic to sensitive animals or humans.

Do not let your pet ingest flea powder of any sort. This can be tricky with pets that groom themselves, such as cats and ferrets. With dogs, if you brush the powder in, your dog will not ingest much if any powder.

Borax and salt

Also known as sodium polyborate, sodium tetraborate, sodium borate. The chemical is related to boric acid. This is present in a variety of household products. Sprinkling 20 Mule Team Borax, the kind you use in laundry (*not* the hand soap Boraxo; the soap added to can be toxic to your pet) on the carpet and upholstery will dry out the deposited flea larvae. The procedure is to vacuum the house, sprinkle borax or salt using a sieve on carpet and upholstery (and under the pillows, under the furniture); sweep with a broom to settle the borax into the carpet and then vacuum again. Some people leave it on for a few days before vacuuming, but this runs the risk of abrading the surface of the carpet. Don't let your animals eat the stuff. If you use borax, you may need to adjust for this when cleaning your carpets by using less soap. The effects of a borax treatment seem to last about a year or so.

Drawbacks: The chemical borax is abrasive, and 20 Mule Team Borax may abrade your carpets. In addition, there are documented cases of long-term low-level exposure to sodium polyborate resulting in conjunctivitus, weight loss, vomiting, mild diarrhea, skin rash, convulsions and anemia and other similar allergic reactions in humans. If you're using borax as flea control, and your pets (or family) are showing loss of appetite, eye or skin problems, anemia or kidney problems, you may want to switch to another flea control method and see if their health improves. Do not apply it to damp carpets as it can take the color out.

Borax is NOT advisable where you have pets which groom themselves, e.g., cats and ferrets. They can ingest enough to harm them if the borax is not settled deeply enough into the carpet (October 1992 of Dog Fancy). Symptoms of acute poisoning include diarrhea, rapid prostration and perhaps convulsions [these occurred when borax was scattered openly for cockroach control].

There are various products that are applied in the same way, such as PEST-X. Check these types of products to see if they contain borax or boric acid. If so, the above commentary applies to those products as well. Otherwise, check the ingredients against the other ingredients discussed elsewhere.

Some people use salt instead of borax. Provided that you do not live in high humidity areas, this is an alternative. Since salt absorbs water, salt in carpet in an unairconditioned house in Florida (for example) would mean a damp carpet -- later rotted or mildewed.

A cheap source of boric acid powder is "Terminator". Available in hardware stores. A 5lb can of 100% boric acid powder is about $22; a 30lb can $54. Customer service # is 800-242-9966.

Vacuum

Put flea powder in the vacuum cleaner bag to kill any fleas that you vacuum up, otherwise they will crawl back out. You should change the bag in your vacuum cleaner after a round of flea-cleaning in any case. Moth balls can also be used, but they are pretty toxic. Sometimes people put (cut up) flea collars in the bag, but it is not clear that this is effective, and if the collar contains dichlorvos, is NOT recommended.

Flea collars

See Consumer Reports, August 1991. Flea collars aren't 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.

Newborn animals

Very young animals can die from overinfestation of fleas. They are small enough that they can become dangerously anemic within hours, and are young enough that they will be poisoned by dipping chemicals. Consult your vet immediately if you have a less than 8-10 week old kitten or puppy with a bad case of the fleas. Do not attempt to "dip" them, you can easily kill them this way.

Symptoms of anemia: if flea-infested baby animals become lethargic, weak, and pale, you may have *only hours* before they die. A good test for anemia is to take your finger, lift the upper lip, and press gently but firmly into the upper gum. The gum will turn white for a moment and then return almost immediately to a pink color. If the gum stays white for more than a couple of seconds, anemia is indicated. Take them to the vet *now*.

If they do not yet appear anemic, use a flea comb on them. You should take steps to prevent infestation by keeping the mother clear of fleas, and regularly (at least every other day) changing and laundering the bedding. While you should not dip them in chemicals, giving them a plain soap-and-water bath can help remove the fleas from their body: wash the bedding at the same time and then use the flea comb regularly to keep fleas from taking hold again. The mildly insecticidal shampoo Mycodex (tm) can be used on kittens, but requires flea combing afterwards anyway because of its mildness.

From Orca Starbuck:

Most flea shampoos, sprays, and powders are not cleared for use on pregnant, nursing or young animals. In addition, the act of bathing, spraying, or powdering a pregnant or young animal can frighten or chill the animal. So most vets are hesitant to recommend ANY course of action if you have pregnant, flea-infested animals. However:

Low concentration pyrethrin products (or allethrin, like mycodex) ARE considered safe. In "Feline Husbandry" pyrethrin is the only flea poison included in a list of chemicals and drugs that are known to be safe during pregnancy. Methoprene is also considered safe, although its use is new enough that it doesn't appear in many of the texts.

Zodiac pyrethrin + methoprene spray for cats is considered safe for pregnant and nursing cats and kittens that are at least 24 hours old! The same is true for the similar spray for dogs. Likewise, the Zodiac premise sprays are safe for use where pregnant and nursing animals and young animals are housed, as long as the spray is allowed to dry before the animals are introduced back into the area.

Since spray can often be upsetting to the mother cat, a paper towel which has been sprayed with Zodiac spray for cats until it is about 1/2 saturated is better. Rub the towel all over the queen (except for her face and nipples) and comb out with a flea comb, and repeat the treatment a week later.

If there are still problems with fleas once the kittens are born, it is quite safe to do the same treatment on the kittens about once a week, starting at a week of age.

Toxicities of different products

According to Steven A. Melman and Karen L. Campbell's "Flea Control" (John R. August, ed. 1991. Consultations in feline internal medicine. WB Saunders & Co., Philadelphia. ISBN 0-7216-2226-7: Chapter 9), pesticides that have caused serious or fatal illness when used ON cats at dosages effective against fleas are:

• Carbaryl (Sevin)
• Chlorpyrifos (Dursban)
• Dichlorvos (DDVP, Vapona)
• Dioxathion (Delnav, Deltic)
• Lindane
• Malathion
• Naled (DiBrom)
• Phosmet (=prolate, Kemolate)
• Permethrin
• Propxur (Sendran, Baygon)
• Pyrethrins (but microencapsulated pyrethrins have no listed problems)
• Ronnel (=Korlan)
• Tetrachlorvinphos (=Rabon)

The following flea-cides used ON dogs are NOT approved for use ON cats (though they're all OK'd for indoor environmental use):

• Amitraz (Mitaban)
• Bendiocarb (Ficam)
• Chlorphenvinphos (Supona)
• Chlorpyrifos (Dursban)
• Cythioate (proban)
• Diazanon (Spectracide)
• Fenoxycarb
• Fenthion (Prospot)
• Methoprene (Precor)

The following have been reported to cause serious illness or death when used ON dogs:

• Carbaryl (Sevin)
• Chlorpyrifos (Dursban)
• Dichlorvos (DDVP, Vapona)
• Fenthion (Prospot)
• Lindane
• Malathion
• Phosmet (Prolate, Kemolate)
• Permethrin
• Pyrethrins (but not microencapsulated)
• Ronnel (Korlan)
• Tetrachlorvinphos (Rabon)

Flea control on rabbits

by Sandi Ackerman

There's a controversy as to which type of flea products are safest for our rabbits. The House Rabbit Society has always said to use a powder that is safe for cats/kittens and in this area of the country our veterinarians have recommended pyrethrin based powders. However, we've recently discovered that while our veterinarians in Washington state are saying to use products that contain pyrethrins, veterinarians in other parts of the country say to use products that contain 5% Carbaryls.

What I've found after considerable research is that there are no specialists who will make a written statement one way or the other as to which product (one, both, neither) is safe for our rabbits. This is because there have been inadequate studies done on rabbits (thank goodness)! But what's a person to do?

I've searched through Medline, which is an on-line medical database containing data going back to 1966. There are many of studies out there about pyrethrins and carbaryls, but the question is: how to interpret them? I've tried to get manufacturers of flea products to talk to me -- no luck. So after gathering all the data that I could find, I called the National Animal Poison Control Center (NAPCC) to verify the following information.

To summarize:

Pyrethrins are considered safe. These are insecticides derived from plants, but in some cases where the dose is too high, they can cause tremors, seizures and death. They act rapidly and have "some residual" effect.

Pyrethroids are synthetic derivatives of natural pyrethrins and are considered to be "more effective insecticides and are less toxic to mammals than the natural pyrethrins"[1]. Allethrin (a synthetic) is said to be safer than natural pyrethrins.

Carbaryls are considered safe and are used on vegetables in our gardens (Sevin). But they too can cause convulsions and death if too high a dose is used [1]. They remain effective from one to three weeks.

The database at the NAPCC contains no reports of problems in rabbits from either the pyrethrin or the carbaryl powders.

It's not these insecticides which are the problem, but rather the enzyme inhibitors in the products! The following are common enzyme inhibitors, also known as synergists, which may be found in flea products:

     Piperonyl butoxide
    Sesamex
    Piperonyl cyclonene
    N-octylbicycloheptene dicarboxamide

These synergists may be added to the flea powder/spray in order to keep the flea from being able to resist the toxic effects of the pyrethrins or carbaryls. How that resistance occurs, is stated as "...inhibiting mixed function oxidases, synergists also potentiate mammalian toxicity."

What this means is that in addition to affecting the flea, these synergists also keep our companions from being able to resist the toxic effects. It is known that problems are more pronounced when the product is applied to the animal's skin, rather than if the animal ingests it while licking it from their hair [2].

A representative of the NAPCC stated to me that they had worked with one company who was producing a pyrethrin flea spray which was causing a lot of problems in cats. After the company reduced the percentage of synergists to 1% there have been no additional reported problems from their product.

So what's the answer? Always read the label of flea products keeping the following figures in mind as a guideline.

     Carbaryl                          5.0% or less
    Pyrethrins                        0.15% or less
    Synergists (see above)            1.0% or less
    Precor (good) keeps insects from maturing

The first recommendation of the House Rabbit Society is to attempt to remove fleas by using a totally non-toxic flea comb. If there aren't too many fleas this may be a good solution (and it helps you to bond with your rabbit). Because of the large volume of rabbits in my home which makes it impossible for me to powder them all, and after speaking with one of my veterinarians, I intend to use flea products (using the above guidelines) on my rabbit's bedding and under their cage.

In conclusion, I'd say that it is advisable to try to get rid of the fleas, and there are good safe powders on the market that will eliminate the little pests. Powders are much safer than flea dips (we receive numerous reports from veterinarians and owners, of flea dips killing rabbits). Please, just pay attention and read the label before you purchase a flea product.

References:
1 The Merck Veterinary Manual, seventh edition p.1665,1669,1501.
2 Snodgrass, H.L. J Toxicol Environ Health 1992 Feb. 35(2) P 91-105.

Systemic products

These have all appeared within the last two years or so. The general market seems to be heating up -- more demand or better research? And the trend is definitely toward a substance on the coat or in the bloodstream to kill fleas.

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 dog's skin and kills on contact (therefore fleas are not required to bite the dog). The substance will wash off, so swimming is recommended against. It is not absorbed into the bloodstream or internal organs. It is a repellant and an insectide, and people are reporting 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. This is applied along the dog's or cat's back and works for a month. After application, watch your pet for signs of lethargy or allergic reaction -- while studies show that there are no adverse effects up to five time the recommended dosage, there are always sensitive individuals. Advantage runs $15-$20 for a dose large enough for a labrador (two vials). 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.

Frontline

Similar to Advantage, but is not water soluble (must use alcohol to wash it off). It can be used on pups, kittens, cats, and dogs. It does not use pyrethrins/permethrins (good news for dogs allergic to these substances). It can repell 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 can be used on puppies (8 weeks or older) and kittens. It has a toxicity rating of LD 50 which is similar to aspirin. Frontline CAN BE TAKEN OFF with Sulf Oxydex Dog and Cat shampoo, manufactured by DVM Pharm. The peroxide in the shampoo deep cleans the sebaceous glands and therefore washes all Frontline away when rinsed.

Knockout

Works like Frontline, but is only approved for dogs. Contains permethrins, and is supposed to repell both fleas and ticks. Active ingredients: Pyriproxyfen: 21[1-methyl-2-(phenoxyphenoxy)ethyoxy] pyridine....0.05% cyclopropanecarboxylate 2.00% inert ingredients 97.95% Also has NYLAR, which is an insect growth regulator.

ProTICal (formerly Defend)

A topical agent, the product is absorbed into the skin and spread through the fat layer; some dogs are sensitive to this. Not approved for cats. Supposed to work for both fleas and ticks, but many reports of tick infestations anyway. Active ingredient is permethrin.

Proban (cythioate) and Prospot (Fenthion)

These are not licensed for use in cats in the U.S. They may be used on dogs. They work on the principle that if you poison the bloodstream, the fleas will die after ingesting the poisoned blood. Several problems: first, you *are* introducing a low level of poison into your pet's bloodstream, and the long-term effects are unknown. Second, this does not help at all the pet that is allergic to fleas and cannot afford to be bitten in the first place.

Program (lufenuron)

From Steve Dudley: 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).

Chitin is a polysaccharide, that along with various structural proteins makes up 25-50% of the dry weight of insect exoskeletons. It is necessary for integrity and strength.

Lufenuron, marketed in the US under the PROGRAM tradename (available by veterinary prescription only), and widely available in Europe, is administered orally with food, in tablet form, for dogs. A suspension form is administered to cats. To maintain effective levels of control for a 30 day period, 10mg of lufenuron per kg of body weight is recommended for dogs. For cats, 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 feces. It was found that after two days of feeding on treated dogs, no adult fleas developed from eggs laid by females feeding on the dogs. 80% control of a flea population takes about 4.5 weeks, as pre treatment flea larvae and pupae in the environment still must complete their life cycles. 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.

This was taken from the following article: A Novel Approach to Flea Control: Systemic Use of Lufenuron. By Rudolf Schenker and Philip A. Lowndes. Ciby- Geigy Ltd., Basel, Switzerland.

Other notes: a version approved for cats (liquid form) is out now. It's also approved for use with nursing mothers. This is not toxic to adult fleas. Program has no warnings or contraindications on the FDA approved package insert; it can be used in conjunction with other flea control products and heartworm preventives. 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 dog be bit by all the fleas in the house for them to produce the defective larvae; this is not acceptable when the pet in question has flea allergies! Finally, for Program to be effective, all animals in the house need to be placed on it.

BioSpot

Topical application, kills fleas, eggs, and ticks. Repels mosquitos. Works for one month. Sometimes turns white hair yellow temporarily. Contains permethrins and IGR. Contraindicated for use in cats.

Homes with pregnant women/crawling infants/baby animals

Specific recommendations from "Flea Control" for houses with pregnant women or crawling infants are for a combination of microencapsulated pyrethrins (eg Sectrol from 3M) and methoprene.

Preventing flea infestations in your next home

Since flea larvae can lay dormant for surprisingly long periods of time, it is always possible for you and your pets to get fleas by moving into a house or apartment in which the previous occupants had fleas.

If this may be the case, you can prevent the potential problem by spraying or treating the place *before* you move in, if at all possible. For example, if the place has been uninhabited long enough that all the adult fleas are dead, methoprene should be sufficient, otherwise use sprays that will also work on the adults.

Conclusion

In general, you will have to use a combination of some of the approaches above. You will also want to launder any bedding and other launderable items to rid them of fleas at the same time. If you comb your pet regularly, you will be able to spot an incipient increase of fleas and make pre-emptive strikes. If you have a bad flea problem, getting your carpet professionally cleaned in addition to other control methods will help in removing potential food sources for the larvae.

People have asked me what my personal methods are. I prefer to use a IGR type of spray. I obtain Vigren (methoprene) from Gardens Alive! and spray my house every four months and also after I have the carpets cleaned. Since I show my dogs (hence exposing them to flea-infested sites), I will take some preventive action before going by spraying them with Ovitrol Plus by VetKem which is a mixture of microencapsulated pyrethrins and methoprene and seems to last a long time, several weeks if they don't go swimming. I have not had a serious problem with fleas for several years, despite living in Southern California. I have also used Borax in the carpet to good effect, but have become concerned about possible inhalant problems and damage to the carpet. Since one of my dogs and my cat have flea allergies, I have not tried out the Program product, nor do I intend to, though I've heard plenty of wonderful things about it.