Choosing a flea control product for your dog or cat — a veterinary dermatologist’s perspective

By Jon Plant, DVM, DACVD

With so many products on the market to control fleas on your pet, how do you choose? Start by asking your veterinarian. They should be able to tell you about which products are most effective in your area. They will also be able to factor in the other pets in your home, how often your pet is bathed, tick exposure, and what other parasites you need to be concerned about. They’ll also take into account your pet’s age, weight, bathing routine, and medications that may interact with some products.

And a word to the wise: don’t buy the look-alike product in the big box store. Just because an active ingredient might be the same doesn’t mean they are equivalent to the real thing in every important respect. As you can imagine, the “inactive” vehicle in which the active ingredients of topical flea products spread across the skin surface is an essential part of the formula for them to be effective. This is where the generic and brand name products usually differ.

To compare some important features of the most common flea control products for dogs and cats, read on…

Bravecto®, Merck Animal Health

Bravecto chew tab
Bravecto

Route: chewable oral, with food

Frequency: every 3 months

Active ingredient: fluralaner

Time after administration to kill fleas: 88% by 4 hours, 100% by 12 hours.

Approved for: dogs only, greater than 6 months and 4 lbs.

Also controls: ticks; may control demodectic mange (off –label use).

Comments: Giving flea control products too infrequently is probably the most common reason products “fail.” Bravecto may be right for the dog owner that has trouble remembering to administer a monthly product on time. Instead, they are challenged to remember to administer something every 3 months! Hmm. Use Itchology for iPhone to set up a reminder, and you won’t have a problem in either case!

Bravecto is generally well tolerated (dogs will actually eat the chewable formulation and there is very little vomiting after administration). The speed of flea kill is good at Weeks 4 and 8, but then decreases by Week 12. However, 100% of fleas are killed within 24 hours of infestation from week 0 to week 12. These nuances may be important in a very flea allergic dog that lives in an infested environment. Where the Lone Star tick is a problem, Bravecto may need to be administered more often.

NexGard®, Merial

NexGard
NexGard

Route: oral soft chew

Frequency: every 1 month

Active ingredient: afoxolaner

Time after administration to kill fleas: 88% by 4 hours, 100% by 8 hours.

Approved for: dogs only, greater than 8 weeks and 4 lbs.

Also controls: ticks

Comments: In a head-to-head comparison, NexGard generally killed fleas quicker than Bravecto over the course of an 84 day study, when measured 12 hours after re-infestation. By 24 hours after re-infestation, both products killed 100% of fleas. We are so much better off quibbling about these relatively minor differences than we were 20 years ago when we were lucky to kill 50% of the fleas with much nastier chemicals! NexGard is tasty and goes down easily most of the time.

Activyl®, Merck Animal Health

activyl
activyl

Route: topical spot-on

Frequency: every 1 month

Active ingredient: Indoxacarb

Time after administration to kill fleas: 93% by 12 hours after first application; 100% by 12 hours after re-infestation on Day 7, 14, and 21; 100% by 24 hours on Day 28.

Approved for: dogs greater than 8 weeks and 4 lbs. Cats greater than 8 weeks and 2 lbs.

Also controls: Activyl Tick Plus for dogs only.

Comments: Indoxacarb itself is not effective, but it is converted into the active molecule in the gut of susceptible insects (bioactivation), whereas mammals break it down into inactive metabolites. This, together with other differences between indoxacarb’s effect on mammals and insects, gives it an excellent safety profile. Like many of the chemicals now used in flea control products, indoxacarb was first developed to control food crop pests. Activyl Tick Plus for dogs also contains permethrin and is only to be used on dogs.

Revolution, Zoetis

Revolution
Revolution

Route: topical spot-on, absorbed systemically

Frequency: every 1 month

Active ingredient: Selamectin

Time after administration to kill fleas: for infested dogs or cats, Revolution takes longer (24-48 hrs) to approach 100% efficacy than some other products. On the other hand, it performs well in dogs and especially cats through Day 28.

Approved for: Dogs over 6 weeks, cats over 8 weeks

Also controls: heartworm disease, ear mites, sarcoptic mange, American dog tick

Comments: The effectiveness of all monthly flea products decreases toward the end of the month. Revolution is a bit slow to start working for a heavily infested pet, but its comparative effectiveness throughout the month makes it a good choice for cats and dogs for prevention of a flea infestation (which is what we should be aiming for in any case!)

Comfortis, Elanco

Comfortis
Comfortis

Route: chew tab, with food

Frequency: every 1 month

Active ingredient: spinosad

Time after administration to kill fleas. Dogs: after dosing, 64% efficacy at 1 hour; 100% efficacy at 4 hours. The speed of kill is slower by Day 28. Cats: greater than 90% efficacy at 2 hours; 100% efficacy at 24 hours post-dosing.

Approved for: dogs greater than 14 weeks and 3.3 lbs. Cats greater than 14 weeks and 2 lbs.

Also controls: Comfortis only takes care of fleas. Trifexis® (essentially Comfortis with the additional ingredient milbemycin) also prevents and controls heartworms, hookworms, roundworms, and whipworms. Trifexis is approved for dogs (only) greater than 8 weeks and 5 lbs.

Comments: The rapid onset of action makes Comfortis or Trifexis good choices for infested pets. For flea allergy dermatitis patients, for which decreasing the chance for fleas to bite is doubly important, Comforts and Trifexis can be very helpful. The spectrum of parasites that Trifexis combats makes it an appealing product, depending on the overall parasite control program recommended by your veterinarian.

The disadvantages of Comfortis and Trifexis are (a) the relatively low palatability of the chew tabs and (b) the significant number of dogs that vomit following their initial dose. The aforementioned decrease in speed of kill during the end of the dosing cycle can also be a problem for some flea-allergic pets. Comfortis and Trifexis should not be given to dogs that are taking ivermectin as an off-label treatment for demodicosis.

Cheristin™, Elanco

Cheristin
Cheristin

Route: topical spot-on

Frequency: every 1 month

Active ingredient: spinetoram

Time after administration to kill fleas: 16% of fleas are killed by 4 hours after application; 100% effective at 12 hours. At Day 28, 97% effective at 12 hours following re-infestation.

Approved for:  cats greater than 8 weeks and 2 lbs.

Also controls: fleas only.

Comments: Following the launch of Assurity, another Elanco product with a higher concentration of the spinetoram, a high incidence of hair loss due to self trauma at the application site was discovered. Assurity was subsequently withdrawn from the market and replaced with Cheristin.

Vectra®, Ceva

Vectra for Cats
Vectra for Cats

Route: topical spot-on

Frequency: every 1 month

Active ingredients: dinetofuran, pyriproxifen

Time after administration to kill fleas. Dogs: 96% effective in 6 hours. Cats: 98% effective in 6 hours.

Approved for: dogs greater than 7 weeks and 2.5 lbs, cats greater than 8 weeks and 2 lbs.

Also controls: Vecta 3D for dogs (with permethrin as an additional ingredient) kills ticks and repels flies and mosquitoes.

Comments: A study comparing the flea feeding activity of dogs treated with either Vectra® 3D or Comfortis® found that the speed of kill and flea bite deterrence with Vectra 3D was more rapid and sustained throughout the month.

The volume of the topical solution for the Vectra products is comparatively higher, which can put off some pet owners.

Soresto®, Bayer

Soresto
Soresto

Route: collar

Frequency: replace collar after 8 months

Active ingredients: imidacloprid, flumethrin

Time after administration to kill fleas. Dogs: kills existing fleas within 24 hours and re-infesting fleas with 2 hours. Cats: 98% effective in 6 hours.

Approved for: dogs 7 weeks or older; cats 10 weeks or older.

Also controls: chewing lice for one month; aids in the treatment of sarcoptic mange.

Comments: three quarters of pet owners apply monthly, spot-on flea products less than 3 times per year! With their long duration of activity, Soresto collars help protect pets throughout the year. Set a reminder to replace the collar with Itchology for iPhone.

The unique polymer structure of the collar and its modern insecticides differentiate it from the ineffective flea collars from years ago. However, the duration of effective flea and tick control is reduced to 5 months with bathing or swimming more than once monthly. It stands to reason that very frequent bathing or swimming could diminish the duration of activity even further.

Advantage II, Bayer

Advantage II
Advantage II

Route: spot-on topical

Frequency: monthly

Active ingredients: imidacloprid, pyriproxifen

Time after administration to kill fleas. 98% existing fleas within 12 hours. By day 28 in cats, only 73% of re-infested fleas were killed within 48 hours in one study. Another study shows a faster speed of kill up to 34 days after treatment.

Approved for: dogs 7 weeks or older; cats 8weeks or older.

Also controls: K9 Advantix II (with permethrin) for dogs also kills ticks and repels mosquitoes. Advantage Multi (with moxidectin) for dogs and cats also controls whipworms (dogs), hookworms, roundworms, heartworms, and ear mites (cat). An off-label use is the control of demodectic mange in dogs.

Comments: the Advantage line of products are generally very effective for flea control in most situations, when used as directed (monthly). If you wait until you see fleas on your pet (which is usually too late, no matter how good of flea picker you think you are), there is a good chance that they have had a chance to breed, lay eggs, and infest your environment. Then you are playing catch up for the next few months, instead of being preventative.

Frontline® Plus, Frontline® Tritak®, Merial

Frontline Plus
Frontline Plus

Route: spot-on topical

Frequency: monthly

Active ingredients: fipronil, (S)-methoprene, etofenprox (Tritak for cats), cyphenothrin (Tritak for dogs).

Time after administration to kill fleas. Frontline® Plus – 100% effective at 12 and 24 hours from 1 day to 28 days post treatment. Tritak® — 90% effective in 1 hour, 100% in 24 hours.

Approved for: Frontline® Plus – dogs and cats over 8 weeks. Frontline® Tritak® dogs and cats over 12 weeks.

Also controls: ticks

Comments: You’ll hear fairly frequently that Frontline “just doesn’t work any more.” Is this real, or simply a perception? Measuring genetically programmed insecticide resistance is tricky, expensive, and rarely undertaken. According to Coles and Dryden “when lack of insecticide or acaricide efficacy is noted by a veterinary practitioner or reported by the pet owner, it is essential to review the history and look for potential treatment deficiency, because the ultimate cause is much less likely to be actual flea or tick resistance.” That said, there is some innate variability in the susceptibility of various flea strains to insecticides, even among those that have not been exposed to the before.

Summary

There are a lot of effective flea products on the market. A perception that a product has not worked is more likely due to trying to stretch out the next dose beyond the manufacturer’s recommendation than anything else. Use a reminder system, like Itchology for iPhone, to keep flea prevention on schedule. Untreated pets in the household or feral animals in the environment are also common sources of treatment failure.

Speed of flea kill is an important measure of efficacy, but not all products have been evaluated in the same manner, so comparisons are imperfect. By all means learn about the products, but ask your pet’s veterinarian for their recommendation!

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What makes dogs itch?

Dogs are taken to veterinarians for itching more than for any other medical problem. But what makes dogs itch?  While there are many possible causes, most dogs that are itchy suffer from one of these six conditions:

  • Flea allergy dermatitis
FAD distribution
Flea allergy dermatitis distribution
  • Atopic dermatitis
  • Food allergy dermatitis
  • Contact dermatitis
  • Sarcoptic mange
  • Demodectic mange

To take a quick look at the body locations commonly affected, the symptoms, and the types of lesions associated with each of these conditions, check out www.itchology.com. Itchology is the app for dedicated pet parents to mange their itchy dogs.

How tracking your dog’s itch level will help your veterinarian

Like a pediatrician relies on a parent to describe their infant’s symptoms, your veterinarian relies on you to describe your dog’s itchiness. He may get a bit anxious or preoccupied during a visit to the vet’s office. During consultations, it is common for dogs to hide any itching behavior (including scratching, biting, rubbing, and chewing themselves). That’s why veterinarians need to find out from you how itchy your dog is.

How do you tell your veterinarian how itchy your dog is?  Until recently, veterinarians may just have asked whether or not she was itchy. But knowing the degree of itchiness and how that itchiness has changed over time, responded to certain medications, worsened when certain foods were fed, or changed with the seasons, weather or pollen count was not information that you could easily gather or share. Now, there is an app for that.

Itchology for iPhone was designed by veterinary dermatologists to help pet owners gather and share the information that can help veterinarians care for your itchy dog.  Recommended by leading veterinary dermatologists who treat dogs with allergies, Itchology is available in the Apple App Store. In the future, it will be available in Android and veterinarians will also be able to view pet data in a web browser.

For more information and a demo video, visit www.itchology.com.

Experience with Apoquel® (oclacitinib) for the treatment of 117 allergic dogs. Part 1: control of itch.

Jon Plant, DVM, DACVD

We started hearing about a new drug to control the itch of allergic dermatitis and canine atopic dermatitis in dogs over 1 year of age at the Vancouver World Congress of Veterinary Dermatology. The research showed some amazing findings. Like most veterinary dermatologists, I was eager to try it in my practice. I started prescribing (oclacitinib) Apoquel® for itchy dogs at SkinVet Clinic in November 2013. As of August 2014, I had treated over 100 dogs with Apoquel.

Dogs with skin allergies can have skin lesions and odor, but the thing that is most troublesome to pet parents (and the dogs!) is the itch that can make them miserable. At SkinVet Clinic, we ask pet owners to grade their dog’s itch level at each examination using a validated visual analog scale (0 – 10). While this is the best method that we have had to grade itch in practice, it gives an incomplete picture of itch severity over time. Soon, pet owners and veterinarians will be able to easily record and view a more complete itch diary using the Itchology app for iPhones (see www.itchology.com for more info and to sign up to get notified when it is released).

This graph shows the owner-reported itch level of dogs before Apoquel blogtreatment and after 1, 3 and 6 months. Both per-protocol data (dogs returned for recommended follow-up examinations at 1, 3, and 6 months) and intent-to-treat (ITT) data (previous value carried forward when dogs did not return for examinations or medication was discontinued) are shown.

  • 117 dogs started taking Apoquel at least 40 days ago (day 0 median = 6.0). Month 1 itch level scores were available for 104 of these (median = 2.5). The ITT data yielded similar results taking into account carried-forward values for the 13 dogs that did not return (median = 2.7).
  • 108 dogs started taking Apooquel at least 3 months ago (day 0 median = 6.0). Month 3 itch level scores were available for 85 of these (median = 2.0). The ITT value was slightly higher (median = 2.5).
  • 91 dogs started taking Apoquel at least 6 months ago (day 0 median of these 91 dogs = 5.7). Month 6 itch level scores were available for 59 of these (median = 2.3). The ITT value was similar (median = 2.5).
  • The percentage of dogs that achieved a level of itch considered “normal” by dog owners (0.0-1.9) was 36.8% at 1 month, 39.8% at 3 months, and 40.7% at 6 months (based on ITT values). Many others were in the “very mild” itch category.

These findings are remarkable, considering that most of the dogs began taking Apoquel during cooler, winter months and follow-up examinations more often occurred during warmer months, when many dogs with allergies would be flaring up. Further, as this was not a rigorous clinical trial, the day 0 itch level was often recorded while the dogs were still taking other medications – from prednisone to Atopica®. (These were discontinued for three days prior to the owner initiating Apoquel, in most cases.) Therefore, it is likely that the day 0 itch level reported here was slightly lower than it would have been with a medication wash-out period.

All in all, Apoquel has performed as expected in my hands. Check back to read my next post concerning Apoquel side effects. And, don’t forget to visit www.itchology.com to sign up for Itchology, a must-have app to help your vet help your itchy pet!

Food allergy in dogs

This month I will discuss food allergy in dogs.  This first installment will describe how frequently food allergy is diagnosed in dogs with itchy skin.  In coming weeks, I will cover the clinical signs of food allergy, diagnosing food allergy, and feeding home prepared and/or raw diets versus commercial diets.

Food allergy, also known as food hypersensitivity or adverse food reaction, can result in skin or gastrointestinal conditions, or both in the same dog.  An allergy is an exaggerated immune response to a substance that most dogs tolerate without problem.  Food allergy may develop for the first time during puppyhood, or as an adult.  Most often they are young adults when signs first begin. Dogs may have eaten a food ingredient for years before developing an allergy to it.

The global pet food industry is a big, competitive business. It is expected to exceed $50 billion by 2015.  It is not surprising that more than 500 new foods are introduced every year to try and capture a share of the market.  Nor is it surprising that they are able to shape consumers’ perception of a condition like food allergy with their large marketing budgets.  According to an FDA web site “this [hypoallergenic] marketing niche was detrimental in two respects. The true nature and incidence of food allergies was clearly overemphasized and misrepresented.”

Walking through the aisles at your local pet store, you would think that every other dog must have a food allergy.  Claims like “hypoallergenic” and “natural” are found on nearly every bag or can of food.   What do these terms mean?  A food can be labeled “natural” if its ingredients are from animal or plant origin, or are mined.  They can still be labeled natural if ingredients are extracted, hydrolyzed, or fermented.  They may also contain synthetic nutrients and still be labeled as natural.

The true prevalence of food allergy in dogs is unknown, but it is almost certainly lower than many pet food companies would have you believe.  Based on a variety of studies, estimates of the prevalence of food allergy range from 9% to 36% of dogs with allergic skin disease. This probably translates to about 1-3% of all dogs.  Atopic dermatitis due to environmental allergens is much more common.  The majority of itchy dogs do not respond to strict diet changes, although it can be an important diagnostic step to take.  In the coming weeks, I’ll discuss the signs of food allergy and how to make an accurate diagnosis.

Best flea control products

My two favorite flea products are Comfortis® and Trifexis®. Both products are once monthly, chewable tablets.  They contain an active ingredient against fleas, spinosad, and ComfortisTrifexis also contains milbemycin which prevents heartworms and controls some important intestinal parasites (roundworms, hookworms, and whipworms).  Fleas take a blood meal within minutes of jumping on a dog. In this way they are quickly killed by spinosad, a chemical that is much, much safer for mammals than for insects by virtue of differences in the nervous system.

We used to hear that “even one bite” could cause flea allergy.  But, the number of mites DOES matter and Comfortis and Trifexis kill fleas more quickly than other products, minimizing the number of bites.  They are not affected by getting wet or bathing in the same way that all topical products are, making them the best option for my patients that often require frequent bathing.  Comfortis and Trifexis are prescription drugs that must be prescribed by your veterinarian.  The choice between the products will depend on your pet’s specific needs and other parasite control prescriptions.