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by Geoff Williams

If you've battled fleas on your dog, you may have wondered whether you should try a flea dip to rid your pup of parasites. Even if you don't know what a flea dip is, you've probably heard the term. But what exactly is a flea dip, and how is this treatment method used?

You have questions. We have answers. Let's look a little closer at flea dips and whether or not they are safe and effective treatment options for our pets.

Where Did Flea Dips Originate?

The term “flea dip” has been around in some form or another since at least the 1870s when pet owners started using the same dips  on their dogs and cats that farmers used to rid their cattle and sheep of fleas, ticks, and lice, according to various accounts in 19th century newspapers.

Pet owners were advised to use "sheep dip," and from there the term eventually spread to reference any concentrated flea-killing chemical that you dilute by adding water. The sheep dip used in the 1800s wasn't terribly dangerous for cattle, sheep, or dogs—the main ingredient was carbolic acid, which can be found in some facial soaps today. But as the 19th century turned into the 20th and pet owners became more distressed over their dogs' flea problems, some of the chemicals in flea dips became much more toxic.

By the 1940s, according to newspaper accounts of the time, the pesticide dichlorodiphenyltrichloroethane (commonly known as DDT) was often used to kill fleas on dogs and cats as part of flea dips. For instance, on October 23, 1945, The Los Angeles Times quoted the president of a local humane society who was using DDT powder on 125 dogs in its kennels and having "wonderful results." The dip worked effectively as a flea treatment, but the problem was that DDT, which killed far more than fleas, was found by researchers to be detrimental to animals, humans, and the environment. DDT pesticide was banned in the United States in 1972 (and later in many other countries) for being extremely deadly.

What Chemicals Are Used in Flea Dips?

Many commercial flea dips have pyrethrins, a concentrated form of Pyrethrum, a natural insecticide that comes from the flowers of chrysanthemum plants. When pyrethrins gets into an insect's nervous system, it shuts it down and results in death, according to the Environmental Protection Agency (EPA).

How Much Do Flea Dips Cost?

Flea dips are generally inexpensive, which makes them an attractive option to some pet owners. You can buy a flea dip from a commercial brand at a pet store for about $10 to $12.

How Do Flea Dips Work?

Flea dips are administered onto a dog or cat’s fur with a sponge, or pet owners can pour the mixture over a pet’s back. Most flea dip products sit on a pet’s skin and coat and are not washed it off. The pyrethrins in the formula then get to work to kill the fleas.

"The dip is a concentrated solution,” says Brian Ogle, an anthrozoology instructor who specializes in pet and animal ownership at Beacon College in Leesburg, Fla. “The animal can either be dowsed by pouring the concentration [on the fur] and rubbing it over the body or by submerging the animal. The animal is then allowed to air dry."

But Ogle says that flea dips are no longer the safest and most effective treatment for fleas. "This method is typically not done any more due to health concerns," he says.

Are Flea Dips Safe for Pets?

Broadly and cautiously speaking—yes, flea dips are safe for pets. But it’s important to keep in mind that flea dips have to be administered correctly with the proper dosage in order to be safe and effective.

"It's best to use a dip under the direct orders of a veterinarian," Ogle says. "Recent research suggests there have been as many as 1,600 pet deaths linked to the use of pyrethroids, a common ingredient in many household insecticides." That said, many experts, including Ogle, recommend avoiding the use of flea dips on puppies under four months, and most veterinarians are reluctant to use them on cats of any age.

Liza McVicker Guess, DVM, is one of those reluctant veterinarians. She is an assistant professor who supervises veterinary students on rounds at the Veterinary Medical Center at Ohio State University in Columbus.

"Cats are especially sensitive to the effects of pesticides so you have to be extra careful with them," she says. "I have seen [cats] suffer and require treatment from over-the-counter flea treatments. The prescription drops and pills have been through rigorous testing and usually come with guarantees if purchased at a veterinarian's office."

For cats, the probability for risk of fatal poisoning by pyrethroid is too high to consider using any type of flea medication or product that contains this ingredient. If you have a stubborn flea infestation on your cat, the best course you can take is to see your veterinarian for advice and treatment.

Flea Dip Dangers: What You Need to Know

Flea dips may also pose a risk to humans if not handled properly. Pyrethrins that are used in these commercial dips may cause numbness, itching, burning, or stinging if they come in contact with a person’s skin, according to the federal government’s Agency for Toxic Substances and Disease Registry.  If ingested, the ingredient could cause dizziness, headaches, and nausea.

Many flea dips contain cautionary language that tells users to wash their hands thoroughly with soap and water after handling the product, and include a warning to remove and wash clothing if clothes come in contact with the treatment. Some flea dips even recommend that users wear protective eyewear. "When it comes down to it, flea control medications are pesticides and they are toxic," Guess says.

Other flea and tick medications on the market, such as pills and drops that are placed on a pet’s back once per month, are easier to administer and often safer for both pets and humans than flea dips, says Guess.

"If you have having a flea problem I would absolutely recommend seeing your veterinarian before using flea products," she says. "Fleas are a very common parasite, and we have a lot of knowledge and experience with treating them.”

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