, Salem, MA

March 22, 2013

Dispelling myths about pesky fleas

Vet Connection
Dr. Elizabeth Bradt

---- — Fleas are nasty parasites that are hard to eradicate. Thankfully, veterinary science has given us effective ways to control these pests, bringing relief to our dogs and cats. But what happens when people think the Internet or a local store has a better solution?

Anyone who suffered through an infestation of fleas last year knows these parasites are programmed for survival. In ideal conditions, fleas can complete their life cycle in just 12 days, adding 2,000 new offspring and increasing their population exponentially every two weeks. That means that two weeks after 1,000 female fleas are born, there may be 2 million fleas in the environment. It can take six to eight weeks of home and pet treatment to annihilate the parasites.

Fleas carried and spread the bubonic plague in the Middle Ages, and today, they are still capable of spreading the plague and a host of diseases such as cat scratch fever in cats and humans, tapeworm, feline infectious anemia (mycoplasma haemofelis), and a rickettsia disease transmissible to both humans and cats that causes fever, flu-like symptoms and a rash. Understanding how to control this life cycle and killing adult fleas helps your pet — and your home — remain flea-free.

Flea Myth #1: Fleas go away during winter months. Although a good part of the country sees a decrease in flea cases during colder months, fleas can survive by taking advantage of our human comforts. Fleas thrive at temperatures above 65 degrees, making our homes a perfect winter refuge. The cocoon stage can actually survive up to five months in cooler temperatures — allowing the next generation of fleas to hatch and attack our pets in the spring.

Flea Myth #2: Natural remedies like brewer’s yeast and garlic are safe and effective flea control methods. For many pet owners, avoiding man-made chemicals and “going green” is important. Garlic, for example, is purported to kill fleas, but the only study conducted showed no effect. Organic and natural remedy products are not only often ineffective at controlling fleas, but sometimes even cause illness in pets.

Flea Myth #3: Chemical pesticides are harmful to pets and to the environment. Historically, this is true. The Environmental Protection Agency banned products containing organophosphates like diazinon due to cancer risks and environmental impact. Advances in pest control provide us with environmentally safe products that can be used on pets. The most current insecticides are sodium channel blockers that are activated once they are contacted and ingested by the flea. The flea does not have to bite the pet to ingest the insecticide. The newest insecticides affect the nerves of insects and are nontoxic to mammals. Many of the insecticides we use on our pets are used on food for human consumption. Your family veterinarian has both oral and topical products providing effective and immediate flea kill. Additionally, these products are harmless to both pets and children.

Flea Myth #4: Fleas are resistant to these new chemicals — even products my veterinarian carries. With stories of “super-bug” bacteria making headlines, it’s easy to imagine a super flea shaking off pesticides like water. Veterinary products have a great track record of killing fleas and experts state resistance to these products has not occurred. Most perceived product failures are likely due to excessive numbers of fleas or inappropriate application.

Flea Myth #5: There is no difference between flea products purchased from pet stores and your veterinarian. Unfortunately, this myth is the cause of many emergency room visits — and pet deaths. Pet store products may contain older insecticides and chemicals. This could mean that they are simply less effective, but in some cases, these products have actually killed pets — especially cats. In an attempt to save money, well-meaning owners have used dog products on their cats, causing the cat to seizure uncontrollably — creating a potentially fatal emergency.

Pet stores, Internet pharmacies and big-box stores may carry diverted pet product. That is product that was sold to the store by an individual rather than the manufacturer. The source, warehousing and chain of custody of the product are unknown. In this day and age of contaminated and unreliable pet products in the marketplace, this can pose a risk to your pet.

Your veterinarian has access to at least 10 nontoxic flea products and can recommend what’s best for your dog or cat.

See your veterinarian for the best advice on avoiding flea infestation. To learn more, visit and see a library of videos that will help you better understand these pesky pests.


Dr. Elizabeth Bradt is a 1986 graduate of Tufts University Cummings School of Veterinary Medicine and is the owner of All Creatures Veterinary Hospital in Salem ( She is a member of the American Society of Veterinary Journalists. Email your pet questions to Please title your email “Vet Connection.”