Visiting Veterinarian

A flea in her ear

By Michele Gerhard Jasny V.M.D. - September 27, 2007

Cats pulling out their hair, breaking out in scabs all over. Dogs with big gooey hot spots under their ears and on their flanks. Fleas fleeing in all directions as I run my fingers through my patients' fur. I'm not sure why but this fall is one of the worst flea seasons I've seen in a long time. Before the advent of "total body" flea control products like Frontline Plus, Advantage, K9Advantix, and the like, I spent every summer and fall up to my elbows in flea shampoos, dips, sprays, collars, and powders. Anything to fight the army of critters that invaded our homes and left our animals frantically scratching. Maybe it's the weather this year. Maybe the bugs are developing resistance to some of these products. Maybe it's global warming. Whatever it is, it's time to go back to basics and review the life cycle of the flea.

The adult flea is a wingless, six-legged insect that spends the majority of its time living on your cat or dog. Although adult fleas may hop off into the environment, they much prefer to rove on Rover. Mama flea must take a blood meal, biting Rover, then deposits her tiny, white eggs on his back. When Rover scratches, eggs fall onto his bed, your bed, the carpet, the couch. The eggs hatch into larvae... nasty, squirmy little worms that are geotropic, which means they like to go downward. They also dislike light. The larvae burrow deep in the shag rug, between the floorboards, anywhere that is "down and dark."

As Rover scratches, he also sheds dander. To flea larvae, this means lunch. After feasting on dander and other organic debris, they spin sticky cocoons and turn into pupae that rest, securely glued to whatever surface they are touching. You can run the Electrolux right over them and not dislodge them. Pupae can remain dormant for extremely long periods of time, waiting for optimum conditions. They are stimulated to hatch by the presence of vibration and carbon dioxide. Why? Think about it. When Rover walks across the rug and exhales, what do you get? Vibration and carbon dioxide. It's like ringing a dinner bell, signaling that a warm-blooded host is in the vicinity. The pupae hatch into new adult fleas that hop onto Rover and it starts all over again.

How they work

So how do we break the cycle? Begin by using a total body flea control product. There are many available, both through veterinarians and over-the-counter. Some work better than others. Each has its pros and cons. For this article, I am limiting our discussion to Frontline Plus, Advantage, and K9 Advantix. When you apply a dose of one of these to Rover, it will kill the adult fleas. This may take up to 12 hours, so be patient. If you continue to see live fleas on Rover after a day, it is usually because new adults are hatching and hopping on board. Do not despair. The product is still on Rover. It just takes a little time to kill this new load of fleas. All these products claim to kill the adults before females have a chance to lay eggs. The fleas do not need to bite Rover to be killed.

Okay, you are applying total body flea control faithfully. Your living room still looks like a flea circus. How come? First, be sure you are using your products correctly. Read labels. Keep Rover dry for two days before and two days after flea product application. These products spread via the oils on his skin. Bathing and swimming rinses away these natural oils.

"Wouldn't it be good to use a flea shampoo first?" you ask. Not really. All flea shampoo does is drown a few fleas. Shampoos have no residual effect. New fleas will re-infest Rover within days. Better not to shampoo and leave all the skin oils to facilitate delivery of the products. In the old days, we followed shampoos with leave-on dips. They smelled nasty, only lasted for a week or so, and were far less effective than current products. The new products are much better and also result in less human insecticide exposure.

I usually apply them in the evening, after my kids have gone to bed, when I know they will be away the next day. By the time the girls get home from after-school activities, the product has had almost 24 hours to distribute. I suggest they do not touch any visible wet spot on the pets and to wash their hands after playing with them. On dogs, apply the product directly to the skin in several areas down the back. If you're sloppy and pour the stuff on the fur instead of the skin, it won't work well. On cats, apply it in one spot on the back of the neck, far enough down that it doesn't drip onto their foreheads, but not so far back that they can twist around and lick off.

Topical, not oral

Read labels! See that big "K9" on the K9 Advantix? That means you don't put it on your cat! There are several products that are safe for dogs but can be lethal to cats. And remember, these are topical products, not oral. I've had a few people put the stuff in their pets' food instead of on the skin. All animals in the household should be treated simultaneously. In mild to moderate flea infestations, monthly usage will eventually break the flea life cycle.

What if you're doing everything right and your ankles are still covered in flea bites? In spite of your best efforts, there are still eggs, larvae, and pupae in the environment. Continuing your current procedures might eventually eliminate the fleas, but do you really want to put up with them for another few months? You can expedite matters by treating the environment. Start by vacuuming. Throw away the bag afterwards. Now treat the house with a product that will kill larvae and eggs. (Nothing gets those pesky pupae, but when the new adults hatch, they will hop on Rover where your total body flea control product will take care of them.)

So you want flea bombs, right? Wrong. I am not a big fan of bombs. People have the misconception that these canisters release a mist that "gases" the fleas. Not so. A bomb is simply a delivery method trying to treat all horizontal surfaces. The trouble is, they don't do a very good job of getting insecticide underneath things, like the couch or table. And remember where flea larvae like to go? Down and dark. In my opinion, you are better off buying a "premise spray," then carefully and deliberately spray everywhere. Concentrate on places pets sleep. Protect fish, birds, plants, and food preparation surfaces as the label says. Buy a product that contains "insect growth regulator" to prevent eggs from hatching.

You don't have fleas, you say? If Rover is scratching wildly, and Fluffy is leaping madly from counter to counter trying to avoid the rugs, think again. Many owners miss the telltale signs. Get a good flea comb. Check Rover's coat. You may not find live fleas but if you see tiny black flecks, that's flea - ahem - excrement. Don't believe me? Fleas eat blood. Put that black fleck on a wet paper towel. See a red halo form around it? It's flea poop, and you've got fleas.