Flea Control for Dogs | How to Treat Fleas

There is a great 2015 TED talk by Susan Little, DVM, PhD, DACVM, in which she posits that modern parasite preventatives are largely responsible for bringing dogs (and cats) into our homes over the past few decades. 

“The advances that the veterinary profession has made in achieving parasite control for pets has done more to support the human/animal bond – to really change at a fundamental level the way we interact with our pets – than anything since the rabies vaccine,” she says. Quick and easy prevention of fleas and ticks (which prevents zoonotic transmission of flea-borne and tick-borne diseases, as well as internal parasites such as the tapeworm) has enabled us to bring our pets not just into our homes but also onto our sofas and beds. 

 “It’s because we’ve taken parasites out of the equation that we’re able to have that close relationship with them,” says Dr. Little, a veterinary parasitology professor at Oklahoma State University. 

Perhaps you have to be a certain age to appreciate this point. My own son, who recently turned 30, grew up with a dog on his bed; he’s never known a time when almost every dog had fleas. But I grew up with dogs who all had teeth that were worn flat from chewing their itchy flea bites by the time they were middle-aged. And those dogs all lived outside; the thought of inviting them into the house (much less our beds) makes me itch just to think about it. Fleas were as common as stars in the sky and likely as numerous.

Today’s owners may never have seen a seriously flea-infested dog (with or without tapeworms) – and just as people who have never seen a polio or tuberculosis victim may eschew vaccinations for those diseases, many people seem to regard any use of flea preventatives as dangerous and unnecessary. 

My generation, I guess, is the bridge. I am familiar with how fleas can sharply decrease the quality of life for a dog and cause secondary health conditions such as flea allergy dermatitis and infected “hot spots.” And in the age of social media, I’ve also seen Facebook groups populated by tens of thousands of dog owners who are certain that modern flea-preventative chemicals killed their dogs. While the numbers of dog deaths directly attributable to these products can’t possibly be as many as alleged, it’s clear that they do sometimes cause adverse health effects and even death.

What’s a responsible dog owner to do?

TAKE REASONABLE ACTION AGAINST FLEAS

A middle-ground, common-sense tactic is to use one of the modern-miracle flea-control products, but only when needed, and only as minimally as you can while still preventing fleas. If you’ve never seen a flea on your dog or in your home, don’t introduce these pesticides or medications for no reason! 

If, on the other hand, you’ve found fleas on your dog, or you just moved into a home with a carpet that’s literally hopping with fleas (the latter has happened to me more than once!), it makes sense to protect your dog as quickly as possible from the tiny blood-suckers. 

There are fewer than two dozen reputable flea-control products on the market and many more disreputable ones. It’s wise to familiarize yourself with the active ingredients in and potential side effects of these products, so you can be alert to any signs that they are working as they should, or causing adverse reactions that warrant further action to protect your dog.

TYPES OF FLEA CONTROL PRODUCTS AVAILABLE

There’s any number of tools at our disposal for controlling flea populations, but beware! Each of them offers benefits and poses risks:

• Pesticide-laden (flea-killing) soaps, shampoos, dips, rinses, sprays, and powders. These products were the flea treatments of my youth and are just as dated. These early-generation insecticides may have contained highly toxic carbamates such as carbaryl and propoxur and/or bioaccumulating organophosphates such as chlorpyrifos, diazinon, and tetrachlorvinphos. Many of these products still are sold, even though they are more toxic to animals and less effective at killing fleas than the newer-generation products. 
• Pesticide-laden collars. The first plastic “flea collars” for dogs were coated with toxic, yet highly ineffective pesticides. Today, the material of the Seresto collar (originally introduced by Bayer, now owned by Elanco) is impregnated with pesticides (flumethrin and imidicloprid)that are slowly distributed over the dog’s skin over a period of months. 
• Topical “spot-on” pesticides. These products are administered in a small volume of fluid that is dripped out of a tube into one or more spots on the dog’s back in the area of his shoulder blades. The active ingredients generally constitute a fraction of the volume; the oily carrier liquid helps the product spread over the surface of the dog’s skin. The active ingredients in these products are neurotoxins specific to adult parasites. Some products also contain insect growth regulators, which prevent flea larvae from developing into adults. 

These products are regulated by the U.S. Environmental Protection Agency (EPA). Some are available as over-the-counter products; some require a veterinary prescription.

• Long-acting oral medications. These products are fed to the dog; the active ingredients spread systemically through the dog. When the target species (flea and/or tick) bites the dog, it ingests some of the active ingredient and dies. This parasite-killing action generally lasts about a month. These products are available by veterinary prescription only.

Oral medications are regulated by the U.S. Food & Drug Administration (FDA).

HOW TO CHOOSE THE BEST FLEA CONTROL PRODUCT

Of course, your veterinarian’s recommendation of a product that’s familiar to them is a good start. If your vet strongly promotes a particular product, ask why she likes that one for your dog over all the other possibilities. If she has a sound rationale, great! But take the time to examine the product and compare it to others; unless fleas are hopping all over the vet in the exam room, it won’t hurt to take a day so you can read up on the product she suggests, and possibly call back with any questions you have about other products. 

When considering your options, we also suggest:

• Don’t buy inexpensive flea-control products from grocery stores or “big-box” retail chains. Low-cost products are associated with a disproportionate number of adverse health effects. We don’t recommend products from the following companies: Adams, Hartz, Sentry, Sergeants, or Zodiak.  
• Keep it simple. While it may seem appealing to address as many parasites as possible with a single product, our bias is to go the other way – to treat your dog for only the parasites you know him to have (or those for which you have good evidence to support a suspicion of their presence). If, for example, your dog has fleas, but ticks are not present in your urban environment and you’re certain your dog does not have worms, treat him with something that’s just for fleas!

More ingredients are not necessarily better, despite what the pharmaceutical companies want you to think. When a pharmaceutical company’s patent on a new drug expires, other companies can create and sell generic versions of the same product, usually for less money. When a patent expiration draws close, their owners often add something to the original product, in an effort to create a new patent that will continue to earn money for the company in a protected market. 

This is the main reason that the pharmaceutical companies keep rolling out new products that address more parasites. In almost every case, they’ve added another pesticide, insect growth regulator, or flea-killing medication to an older product. 

The obvious problem from our view is that the more active ingredients a product contains, the more likely it is to have an adverse effect on your dog. So pick the simplest product that addresses your dog’s issue.

• Keep track of any adverse reaction your dog has had to any topical or oral flea-control product. If your dog ever experienced diarrhea, vomiting, lethargy, or any other reaction within a few days of treatment with a particular product, make a big note for yourself in your dog’s health records. Let your veterinarian know, too, so you both make sure you don’t give your dog any products that contain the same problematic active ingredient. 

If your dog has a bad reaction to another product whose active ingredient is in the same class of drugs as the one that caused his first adverse event, make sure you switch to a product with an active ingredient of another chemical class. 

Below, we’ve listed the active ingredients in each of the best-quality products available, along with descriptions of what they do.

• Our bias is in favor of the Seresto collar over a spot-on pesticide, which we’d take over an oral drug. Why? Because if a dog seems to be having an adverse reaction, we can take the collar off and give him a series of baths in an effort to remove as much of the product as possible. The dog can be thoroughly washed if he’s had an adverse reaction after application of a topically applied product, too. 

In contrast, after a dog has digested an oral product, the full dose is working systemically in his body for a few weeks; there’s no mitigating his exposure to the medication.

That said, there are reasons that someone might choose an oral product over a topical one: 

• You may not want to have contact with a topical product as you (or your kids) pet the dog. This could also be true in a multi-pet household where pets groom each other.
• Dogs with longer coats often sport a “greasy spot” for several days after a topical product has been applied. This increases the concern of petting the dog and coming into contact with the pesticide.
• Bathing or swimming soon after application may reduce the effectiveness of topicals.
• Some ingredients used to kill ticks, such as permethrin, are toxic to cats. This can be a problem in a household that includes both, especially if they are friendly with each other. In that case, giving the dog an oral product would be safer for the cat.

HOW TO TREAT FLEAS ONCE YOU’VE SELECTED A PRODUCT

Here are more safety tips to observe after you’ve decided what product you’re going to use on your dog: 

• Don’t leave any flea-control product within the reach of any dog. This goes double for chewable oral medications that contain flavoring agents (which make them more tempting to your dog.) A kitchen counter or dining room table is not a safe place; a motivated dog who has never counter-surfed before can be fatally poisoned by chewing up and consuming a topical product, or suffer serious adverse effects from eating several months’ worth of medication. 
• Read all the label instructions for any product carefully before administering, especially the part about contraindications. 
• If your dog’s weight puts him near a border for the next-higher dosage, we’d recommend using the lower-dosage product. If your dog is at the low end of the weight range, consider doing the math and splitting the chew or tablet to give your dog an effective dose that’s appropriate for her size. 
• If you live in a place where a flea population is entrenched, keep your dog’s protection continuous while you use integrated pest management (IPM) to reduce the environmental population, indoors and outside, too. Management of fleas on pets must occur in conjunction with regular, thorough cleaning of pet resting areas indoors and out. Once fleas infest a home, total control will require a vigilant program that includes vacuuming, eliminating fleas on all the pets in the home, washing the dog’s bedding frequently, and treating outdoor areas where pets rest. 

Using a flea comb on your dog at regular intervals is a good way to monitor the flea population and help you decide when other control measures might be necessary. 

OVER-THE-COUNTER TOPICAL FLEA-KILLING PRODUCTS

PRESCRIPTION TOPICAL FLEA-KILLING PRODUCTS

PRESCRIPTION ORAL FLEA-CONTROL MEDICATIONS

*Not yet approved in the U.S. for control of these parasites, though veterinarians might suggest them as “off-label” treatments
1. Acuguard is the same product as Comfortis. Elanco sells Comfortis as “Acuguard” under the brand name Vethical in VCA veterinary hospitals.
2. Comboguard is the same product as Trifexs. Elanco sells Trifexis as “Comboguard” under the brand name Vethical in VCA veterinary hospitals.