Fleas are the most common dog and cat parasite and flea allergy dermatitis is the most common skin disease of dogs and cats. Allergic signs include itching, hair loss, redness and open or scabbed sores. Fleas are also primarily responsible for passing along tapeworms to dogs and cats, one more reason to be proactive in their prevention. Heavy flea populations may even lead to life threatening anemia, especially for the young. Fleas are such a challenge because they multiply rapidly and like most insects have the ability to rapidly adapt to their environment, including available insecticides. As expected, the newest products tend to be the most effective and they too will yield eventually to the next generation of flea control products. We will discuss the flea life cycle, flea control measures and some flea control products available at this time. There are over 2000 species of fleas and only two that are typically found on pets in North America, Ctenocephalides canis, the dog flea, and Ctenocephalides felis, the cat flea. In the US, the cat flea is by far the most common for both dogs and cats and accounts for almost all the domestic pet flea population. Some people make references to sand fleas which are not pet parasites and really are not fleas at all; they are small orange amphipods found along the beach and hence their other name, the beach flea. The reference to sand fleas probably comes from finding fleas in sandy outdoor areas and inappropriately referring to them as sand fleas.
The Flea Life Cycle
Adult female fleas lay up to 50 eggs a day and 2000 in a lifetime directly in the hair of the host or pet. These eggs are slightly sticky and adhere loosely,falling off when the pet shakes,scratches or otherwise causes the skin to move. The egg stage is not susceptible
to insecticides and is susceptible to insect growth regulators which affect the hormonal system responsible for development of the egg and larva to the next life stage. Eggs typically hatch in two to ten days depending on how favorable conditions are. Fleas like
warmth and humidity to propagate, hence the most severe flea infestations typically occur during the summer months. The newly hatched worm-like larvae move to protected areas where it is dark. They love carpets, bedding, upholstery and rugs and don’t do very well on hard surfaces such as tile, linoleum and hardwood floors. Larvae feed on organic debris and the food of choice is flea feces; essentially undigested dried blood that passes right through the adult flea and is deposited on the host. Adult females can eat up to 30 times their weight in blood per day and excrete up to six times their weight daily. These dried blood packets often take the shape of a comma (,) and are frequently referred to as “flea dirt”. A flea infested pet is like a giant salt shaker, sprinkling eggs and packaged blood meals wherever they go. The larvae grow and molt twice, finally spinning a cocoon where they become pupae. The larval stage lasts an average of 12 days. Larvae are susceptible to insecticides, insect growth regulators (IGR’s) and borates. The now formed pupa or cocoon stage is slightly sticky, helping it to pick up debris from the surroundings and blend in very nicely becoming nearly invisible.
This is the most resistant stage of all, the cocoon wall is very protective and the next chance to interrupt the flea life cycle will be as an adult flea. This is also the reason that adult fleas may be seen for days to weeks after a good flea control program is put into place. The pupa takes about nine days to mature and may remain in this stage for several months. Almost instant hatching is stimulated by heat, vibrations and increased carbon dioxide – telltale signs that a host and a warm meal are nearby. This is why it is common for a family to return from a stay away from home and walk into a flea frenzy. The pupae have had time to mature and are waiting to hatch until they know a victim is within their reach! The new adults instantly begin to feed, mate and the cycle starts all over again. The entire cycle can complete in as little as two and a half weeks. No wonder fleas are so hard to control! Understanding the flea life cycle is essential to knowing how to control these prolific parasites. Modern topical and oral flea products alone may be enough to control the problem and at times it is necessary to treat the premises as well. For indoor pet flea control, treating the yard can sometimes be helpful and generally outdoor treatment contributes only slightly to overall control. Control measures should be concentrated on moist areas such as mulch and shaded areas like under trees, bushes and shrubs. If pets are housed outdoors then the shelter should receive the same control measures as used in a home. There are a number of products available for area treatment in the form of granules and sprays. To avoid excess insecticide exposure don’t allow your pet to traffic treated areas until the granules have been watered in or the spray has had time to dry. Treat at the frequency recommended by the manufacturer and always read and follow label directions carefully.
Treating the House
Over 90% of the flea cycle is in the environment, only about 5% of the cycle is on the pet. Treating the premises then can be critical to an efficient eradication of these unwanted guests. Start by vacuuming the floors several times a week. The vacuum physically removes many flea eggs, larvae and pupae while the vibrations from the beater bar help to cause the pupae to hatch to adult fleas – effectively shortening the life cycle and producing an adult that can now be controlled with insecticides. Spray or fog the house once or twice at two week intervals and possibly again in four to six weeks. Select a product that has both an insecticide and an IGR for a one-two punch and then as always, follow the label directions closely. Sprays are preferred over foggers because the spray can be directed where the product is needed like under beds, nightstands, couches and in closets. Foggers do not reach all areas in equal concentrations and objects like beds serve as an umbrella not allowing the fogger mist to reach the floor beneath. Foggers also require removing or properly protecting fish tanks, removing plates etc from cupboards and all people and pets must vacate the area for a time; sprays do not carry the same restrictions. Wash all pet bedding weekly. There is no need to worry about any special laundry treatment – fleas and their eggs won’t survive the typical washer and dryer cycles. If the bedding can’t be washed or dry cleaned then replace it. Don’t be surprised to see some fleas for the next two or three weeks. These are likely the pupae stage hatching to adults. Don’t panic and spray the house again, continue the vacuuming to remove the fleas you can and to stimulate the hatching. The new hatches will at least shorten the time you will need to continue the house treatment and remember that the pupae cannot be killed with any currently available house treatments.
Flea sprays and dips have been largely replaced with the newer and effective topically applied products. Generally speaking, there will only be a few special circumstances when a spray is indicated (such as a Frontline® Spray) so our discussion will not include them. If the flea problem is mild to moderate then applying a good topical product may be all that is needed. Remember that seeing fleas for a while does not mean the product is not working; these fleas are probably young, newly hatched fleas that have just hitched a ride. The better topicals will reduce the flea population on the pet by 90%+ within 24 hours and be nearly 100% effective in another 24 hours. The flea kill is not however instantaneous; the flea does need to be exposed to the product for a short time before it is lethal. This time requirement coupled with newly hatching fleas early in the eradication period causes many people to believe the treatment is not working and thus they suffer undue frustration. When the flea population is heavy then premise control is mandatory and additional steps may be added as well. Bathing can be very beneficial in giving the pet some relief and washing away flea dirt, flea eggs and some adult fleas. Bathing is not however a significant contribution to the overall flea eradication program due to a lack of residual protection. Bathing can actually diminish the effectiveness of the topical flea control by removing much of the oil from the skin that is the “transportation system” so to speak for most topical products. For many topical flea treatments bathing should not be done for at least one day prior or one day after application. Capstar® is an oral product that kills fleas completely and quickly, in as little as 30 minutes and lasts for 24 hours. It can be used in dogs and cats as young as four weeks of age. One option is to bath the pet and use Capstar® for the first couple of days combined with household or premises treatment then follow up with a residual topical that will last for the next 30 days. This product also has some unique applications such as administering prior to visiting a dog park or dog show and prior to surgery, boarding, or grooming. It is not a preventive and not commonly used as a long term control product.
There are many choices of effective flea control products available to today’s pet owner. Always read and follow label directions and do not use dog-only products on cats! The best flea control program is always a good flea prevention program!! Below is a partial list of available spot on flea products. The list is not all inclusive and does cover the majority of frequently used products currently on the market.
• Advantage®, K9 Advantix and Advantage Multi manufactured by Bayer key flea ingredient is imidacloprid, labeled for 30 day protection
• Frontline Top Spot® and Frontline Plus® manufactured by Merial key ingredient is fipronil, labeled for 30 day protection
• Revolution® manufactured Pfizer key ingredient is selamectin, labeled for 30 day protection female flea egg production is halted immediately
• Promeris Duo for Dogs® Promeris for Cats® manufactured by Forte Dodge key flea ingredient is metaflumizone, may last for 6 weeks, can reapply in 30 days
• Vectra 3D for Dogs manufactured by Summit Vet Pharm, key flea ingredients are dinotefuran, permethrin, pyriproxifen,labeled for 30 days, has some repelling action and contains an IGR
Permethrins are not to be used on cats!
Oral Flea Products
• Comfortis® for Dogs is manufactured by Elanco Animal Health active ingredient is spinosad in a chewable tablet labeled for 30 days with quick control
• Capstar® from Novartis active ingredient is nitenpyram has quick kill and lasts one day
With all the products on the market now, there is NO EXCUSE to have your pet suffer from fleas.