How to Get Rid of Fleas on Pets and Prevent Them From Coming Back

puppy scratching an itch
The No. 1 sign of fleas in cats and dogs is scratching.

An eighth of an inch. That’s about as big as a flea gets. How could something so small cause such a big problem for so long?

These little parasites are persistent, for one thing. In fact, according to scientists, fleas have been around for millions and millions of years. And for a long time, flea control was a difficult challenge. Until recently, the products that were available had issues around safety, efficacy and convenience. For years, our pets were bugged by the itchiness, irritation and more serious problems caused by these pests without any real answer in sight.

Today, your veterinarian can recommend many products that can safely and effectively protect your pet from fleas.

The most important thing an owner can do to protect a pet against fleas is prevent them, says Dr. Michael Dryden, professor of veterinary parasitology at Kansas State University and one of the leading experts on fleas. “By the time an owner notices fleas, it is essentially too late for the animal. The flea life cycle is already occurring, and infestation and disease are already there.” To understand why this is true, it’s important to understand a little bit about fleas and their life cycle.

More Than Meets the Eye

It should be obvious if your pet has fleas, right? Unfortunately, not always. Even if you’re the most attentive pet owner and you’ve never seen a flea on your pet, your house could harbor a substantial flea problem.

Fleas are not that easy to spot on a pet. Not only are they tiny, they are also usually very well hidden by the coat of most animals. So unless you’re actively looking for fleas, you might not know they’re feeding on your favorite four-legged friend. A telltale sign that might be more obvious is “flea dirt.” These tiny dark specks on your pet's skin or bedding are actually flea feces containing digested blood. If you see what you suspect is flea dirt but you’re not sure, put the specks on a piece of white cloth or paper and wet them. If the specks turn red, you’ve got flea dirt.

Because adult fleas live most of their lives on a host (namely, your dog or cat), this is probably the only stage of the flea life cycle you’re likely to encounter. However, adult fleas are just the tip of the iceberg. Within a few days of feeding, the adult female flea begins to lay eggs, as many as 40 to 50 per day. Within a few weeks or months, she can lay hundreds or even thousands of eggs. And that’s just one flea.

Because of these tremendous reproductive abilities, adults usually make up only 5 percent of the fleas in the environment, with the other 95 percent of the population being in earlier stages. Untold numbers of tiny eggs, larvae and pupae (the cocoon stage) can be hiding out in the rugs, carpets, furniture and bedding throughout your house.

The Facts About Flea Allergy Dermatitis

Once they get to be adults, fleas need to find a host to feed on. And that’s where the problem often starts for pets.

How can you know if your pet has fleas? The No. 1 sign is scratching. If you have a dog, you may notice that he bites, scratches or rubs a lot around his tail, back legs and abdomen. If your cat has fleas, other areas of his body, particularly the head and neck, may be affected as well. And though cats are famous for keeping themselves fastidiously clean, if your feline friend can’t seem to stop grooming, this can be another sign that she has fleas.

“When fleas consume blood, they inject salivary proteins into the bite area,” Dr. Dryden explains. Some pets have a severe allergy to flea saliva, a condition called flea allergy dermatitis, or FAD. After being bitten, these pets will experience a prolonged reaction that causes them to be intensely itchy. Flea allergy dermatitis can strike any dog or cat and is typically characterized by skin irritation, hair loss and open sores that can leave the skin vulnerable to infection.

Flea allergy dermatitis can make an animal miserable. If your dog or cat is diagnosed with this problem, eliminating fleas and then making sure they stay away from your pet permanently is absolutely essential.

The problems that fleas cause can go more than skin deep, though. Fleas are often infected with tapeworm larvae. If a dog or cat ingests an infected flea, the tapeworms will be released inside the pet and go on to infect its new, larger host. Flea dirt (flea feces) also may harbor a bacterial agent that can cause cat scratch disease in people, which is often transmitted by an cat scratch or bite.