Introduction

Topical and oral flea control treatments are most effective

Fleas are not something that will disappear from a cat or dog without help. In fact, ignoring a minor flea problem can quickly lead to an infestation. Female fleas can lay up to 50 eggs per day, many of which may fall off and land in carpets, bedding and furniture. Once the larvae hatch, they remain inactive in a cocoon for weeks or even months. Unsuspecting pet owners may think the problem is resolved after killing the adult fleas, but the life cycle will repeat weeks later unless eggs and larvae are prevented from maturing into adult fleas.

Fleas are more than an annoyance -- they can affect the health of their host dog or cat. When a large number of fleas are present, the blood loss to the animal can be life threatening. Often the flea saliva triggers allergies, and the itching and scratching that ensue can lead to a more serious skin infection. Additionally, pets can contract tapeworms from infected fleas. If you notice your pet scratching, check the skin for a dark brown insect about the size of a sesame seed. If you spot fleas, the first course of action should be to contact a veterinarian for advice on treatment.

To provide immediate relief, your vet may recommend a monthly topical treatment (also called spot-on products) or an oral medication to stop adult fleas from biting and to kill them within hours or days. Topical treatments are squeezed out of a tube and applied between the pet's shoulders or along the back. Oral medications are often preferred in households with children, or  with other pets that shouldn't come in contact with a topical treatment until it dries.

A second approach to flea control is products that contain insect growth regulators (IGRs), which prevent eggs from hatching and larvae from maturing into adult fleas. Products with an IGR can be used to prevent the development of a serious flea problem (should adult fleas crawl onto your pet, the eggs they lay will be sterile) or to prevent a re-infestation on a pet that was recently treated for a flea problem. Some topical flea control products contain both types of flea fighters, but oral products usually contain one or the other. The majority of topical and oral flea control products are available without a prescription from vets, pet stores or online retailers of pet products.

In researching this report, we found useful information at VeterinaryPartner.com, a resource for the veterinary industry. This site has an article by vet Carol Foil, which explains the pros and cons of each product and identifies the ideal circumstances for each. An informative blog entry by Eric Barchas at Dogster.com is also a must read; it gives his assessment of topical treatments, oral medications and other flea control products from his 10 years working as a vet.

Elsewhere, we found reviews of flea control products at a few veterinary websites. The UK-based Feline Advisory Bureau compares the benefits of several flea-treatment products specifically for cats, although not all of the products are available in the United States. We also found a large number of reviews of topical and oral flea products by pet owners at Amazon.com and online retailers of pet supplies, including Petco.com, the 1-800-PetMeds website and PetSmart.com.

Pet owners who are concerned about the ingredients in topical flea treatments can find answers in the directory of flea products at SimpleSteps.org, which is sponsored by the Natural Resources Defense Council (NRDC), an environmental action group. Here, flea products are assigned a risk level rating of one to three paws, with one being the lowest level of toxicity. Overall, oral flea medications have a lower risk rating than topical treatments.

Flea control products to avoid

If you spot fleas on your pet, your first thought might be to use a flea control shampoo, dip, spray or powder to kill them. "Shampoos are less effective than sprays, dips or spot-ons because they have little residual activity." says vet Carol S. Foil, writing for VeterinaryPartner.com. This means that other fleas in the environment can still crawl onto the pet and begin feeding and laying eggs. Although these products may be a first line of defense to stop fleas from biting and give your pet immediate relief, a topical or oral medication, along with treating the environment is generally necessary to prevent fleas from re-emerging.

Experts and owners agree that flea collars are largely ineffective at eliminating fleas compared to topical and oral flea control treatments; therefore, we don't include a flea collar in our Best Reviewed section. Furthermore, the NRDC conducted a study on the toxicity of flea collars and found elevated neurological and cancer risks to humans. After dogs and cats wore flea collars treated with tetrachlorvinphos or propoxur for two weeks, a laboratory tested residue levels on the animals' fur. The findings reveal that half to three-quarters of the pets had "enough residue on their fur to pose significant neurological risks for toddlers who spend about two hours per day with their pet." The study also found a cancer risk "50 to 500 times greater than what the Environmental Protection Agency (EPA) considers acceptable" in adults and an even higher risk for children.

We also saw warnings from several sources about topical products containing chemicals known as pyrethroids, especially permethrin. The EPA classifies it as a likely human carcinogen, and it has also been linked to allergies and asthma. While permethrin is approved for flea control in dogs, the chemical is highly toxic to cats. The Feline Advisory Bureau advises "great caution" in using permethrin-based products if there are cats in the home, saying that it may be wise to keep cats separated from flea-treated dogs for several days.

Several veterinary websites also offer their own warnings about products containing permethrin, and at Dogster.com, vet Eric Barchas says that permethrin-based products such as Bio Spot "are quite ineffective and extremely likely to cause severe adverse reactions in pets." Although this product does earn fairly good ratings from users at Amazon.com and Petco.com, the safety concerns voiced by some experts about permethrin are significant enough to give us pause, and as a result, we don't include any products that contain it in our list of Best Reviewed products.