Is your dog or cat scratching due to fleas?! Yikes!!! Do you end up scratching your own head when trying to select the right flea product for your pet? The seemingly endless options of flea, tick, and heartworm preventives can be overwhelming, but The Meowing Vet is here to help! We discuss the actions of common ingredients found in these products and explain why purchasing a preventive from your veterinarian may be safer than an over-the-counter option. And best of all, we provide an extremely handy downloadable chart breaking down the pros and cons of popular flea, tick, and heartworm products currently on the market.

Keep reading to download your chart below…

What should I discuss with my veterinarian?

Always consult with your personal veterinarian prior to administering a flea, tick, or heartworm preventive to your pet to ensure that you are choosing a product that’s safe for your dog or cat and are dosing appropriately (by your pet’s accurate body weight, the appropriate frequency between dosing, etc.). Many veterinary clinics may also offer coupons or rebates for particular products, so be sure to ask your vet to start saving!!!

What do we mean by a “prevention” product?

Flea, ticks, and heartworms are all parasites, meaning they feed and live inside or on another living being (for matters of this article… your pet!). Ectoparasites (such as fleas and ticks) live on the surface of their hosts’ bodies while endoparasites (like heartworms and intestinal worms) live inside the body. The preventive (or preventative) products to be discussed are often termed antiparasitics or parasiticides, and they may work by killing and/or preventing infection or infestation by these common parasites.

The products discussed below are popular veterinary-manufactured preventives marketed primarily to the United States, Canada, the United Kingdom, Ireland, Australia, and New Zealand. This is not an exhaustive list and simply reflects availability as of May 5, 2017. Veterinary pharmaceutical company mergers and takeovers may cause the branding and availability of these products to vary with time. Some products mentioned may not be available in your country. Always ask your vet for advice concerning the current products available in your area. Based on your region, your vet may advise you to use a preventive year-round… even in the winter months.

What kind of parasites are we talking about here?

Fleas: Flea products mentioned refer to those effective against Ctenocephalides felis, the most common flea species infesting dogs and cats. Adult fleas lay eggs, which hatch into larva that later enter a pupa stage before hatching to later become an adult flea. Fleas may linger off your pet in the environment, including inside your home… particularly in your pet’s bedding or carpet. Therefore, pest control also includes washing your pet’s bedding and vacuuming regularly rather than relying solely on preventives. Some flea products kill adult fleas only while others attack immature fleas (eggs, larvae, pupae) as well, protecting your pet as well as your home from re-infestation. Even indoor-only pets are at risk of fleas as these sneaky insects can sneak through tiny cracks into houses.

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Need a bit of entertainment to go along with all this learning? Else-Vet to your rescue! Prepare to be mesmerized by the witty and informative (and a little naughty) cartoons on veterinarian Dr. Simanovszky’s Youtube channel: Else-Vet. Here’s a little teaser on the flea life cycle…

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Heartworms: When discussing heartworms, we are referring to Dirofilaria immitis*, which is transmitted to your dog or cat via an infected mosquito bite. Based on your geographical location, your dog or cat’s risk of acquiring heartworm disease may vary, so discuss with your veterinarian the importance of heartworm prevention for your pet. Your dog should have an up-to-date heartworm test prior to the use of products intended to prevent heartworm infection because the use of these products in a heartworm-positive dog can be dangerous. For this reason, you should only purchase heartworm preventative medicines from your vet. Many heartworm preventives may also act as a monthly dewormer to rid or control gastrointestinal parasites in your pet. In areas of the world in which heartworm disease is a low risk, the norm may be monthly deworming with other medications rather than those that also prevent heartworm infection.

*[Please note that when referring to heartworms, I am not referring to Angiostrongylus vasorum (a canine lungworm also called the “French heartworm” that occurs in parts of Europe, including the U.K., Ireland, and France). Disease severity and treatment differs between this lungworm and true heartworm infection.]

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To learn more about heartworm disease in dogs or cats, click here.

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Ticks: The consideration of tick products addressed in this article is primarily based on common ticks found in the United States:

1. Dermacentor variabilis (American dog tick): can transmit Rocky Mountain Spotted Fever, some forms of Ehrlichia, and feline Cytauxzoonosis* (*in research settings) while also causing tick paralysis in dogs (as can its relative, Dermacentor andersoni, the Rocky Mountain wood tick)
2. Ixodes scapularis (deer tick or black-legged tick): the vector of Lyme disease in dogs and humans; also transmits certain forms of Anaplasma
3. Rhipicephalus sanguineus (brown dog tick): a potential carrier of Ehrlichia, Anaplasma, Babesia, Hepatazoonosis, and Rocky Mountain Spotted Fever
4. Amblyomma maculatum (Gulf Coast tick): may transmit canine Hepatozoonosis and can also cause tick paralysis; Amblyomma americanum (Lone Star tick): the most common vector of Cytauxzoonosis in cats and can also spread Tularemia and Ehrlichiosis

Various other ticks responsible for tick paralysis, primarily those in Australia (such as tick species like Ixodes holocyclus), may or may not be prevented by use of the discussed products. As I am a veterinarian based in America, always consult with your local vet if you live in an area of the world with other tick-borne disease concerns, including paralysis ticks.

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Learn how to protect your dog with our article on Lyme Disease.

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What are common active ingredients found in most preventive products, and how do they work?

(…plus, a few other ingredients used to treat common parasitic infections in dogs and cats…)

Fair Warning: This will be you after browsing through this boring (yet important) list of chemical ingredients…

• Afoxolaner: an isoxazoline (a newer drug class); affects the neuromuscular system of fleas, ticks, and many flying insects (such as mosquitoes and flies), causing paralysis of these parasites
• Amitraz: a formamidine; disrupts the neurological system of ticks and mites
• Beta-cyfluthrin: a pyrethroid (a synthetic version of the less toxic yet less effective pyrethrin; many pyrethroids end in –thrin); cause paralysis of a variety of ectoparasites; pyrethroids can be very toxic to cats if administered in high concentrations, resulting in tremors, seizures, and sometimes death
• Carbaryl: a carbamate; works similarly to organophosphates, causing nervous system abnormalities in many ectoparasites and endoparasites; although not quite as toxic as organophosphates, never use simultaneously with an organophosphate product
• Chlorpyriphos: an organophosphate (older chemical class originally developed as a tear gas; many organophosphates contain the root terms phos, phosphate, phosphore, or phore); works similarly to carbamates, causing impairment of the nervous system of a variety of parasites (by inhibiting acetylcholinesterase, which affects neurotransmitters); can be extremely toxic, especially to cats, causing SLUD signs (salivation, lacrimation or excessive tear production, urination, and defecation), chronic toxicity to the nervous system, convulsions, respiratory failure, and death; never use simultaneously with a product containing a carbamate; avoid altogether if possible
• Cyfluthrin: a pyrethroid; (see beta-cyfluthrin)
• Cyphenothrin: a pyrethroid; (see beta-cyfluthrin)
• Cypermethrin: a pyrethroid; (see beta-cyfluthrin)
• Deltamethrin: a pyrethroid; (see beta-cyfluthrin)
• Diazinon: an organophosphate; (see chlorpyriphos)
• Dichlorvos: an organophosphate; (see chlorpyriphos)
• Dinotefuran: a neonicotinoid; affects the nervous system of insects (similar to spinosyns); low risk of toxicity
• Emodepside: a cyclic depsipeptide; a dewormer: causes paralysis of various intestinal parasites (example: Profender®, a topical dewormer for cats)
• Etofenprox: a pyrethroid; (see beta-cyfluthrin); don’t let this name confuse ya… although etofenprox does not end in -thrin, it is indeed a pyrethroid
• Febantel: a probenzimidazole; a dewormer with similar action to benzimidazoles (such as fenbendazole)
• Fenbendazole: a benzimidazole; a dewormer: affects microtubule assembly and enzyme action of some intestinal parasites, including whipworms and Giardia
• Fenvalerate: a pyrethroid; (see beta-cyfluthrin); don’t let this name confuse you either… although fenvalerate does not end in -thrin, it is in fact a pyrethroid
• Fipronil: a phenylpyrazole; affects the nervous system of insects, ticks, and mites; very toxic to rabbits and fish/aquatic life
• Fluralaner: an isoxazoline; (see afoxolaner); long-lasting product
• Flumethrin: a pyrethroid; (see beta-cyfluthrin)
• Imidacloprid: a neonicotinoid; (see dinotefuran); may be an environmental toxin to bees
• Indoxacarb: an oxadiazine (newer pyrazoline-type drug class); affects the nervous system of insects, such as fleas; not much insect resistance to this product at this point in time
• Isopropyl myristate: degrades the cuticle (the waxy protective covering of many hard ticks), causing bodily dehydration and death of these ticks
• Ivermectin: a macrolide (macrocyclic lactone); impairs the neuromuscular action (including feeding capabilities) as well as reproduction of several internal and external parasites (including heartworm larva); always follow your vet’s safety instructions as improperly high doses of this drug can be dangerous to dogs (such as collies and collie mixes) with an abnormality of the MDR-1 gene, allowing certain drugs (including ivermectin) to enter the brain, causing central nervous system impairment
• Lambdacyhalothrin: a pyrethroid; (see beta-cyfluthrin)
• Lime sulfur: a malodorous yet overall fairly safe pesticide used in dips and dusts for ectoparasite control (including mange mites and fungal ringworm); can cause skin, eye, and nasal tract irritation
• Lufenuron: an insect development inhibitor; prevents development of flea eggs by preventing them from hatching to then later develop into adult forms
• Melarsomine: a benzene sulfonamide; an aresenic-based product used to treat adult heartworm infections in dogs
• Milbemycin oxime: a macrolide (macrocyclic lactone); (see ivermectin)
• Moxidectin: a macrolide (macrocyclic lactone); (see ivermectin)
• Nitenpyram: a neonicotinoid; (see dinotefuran)
• N-octyl bicycloheptene dicarboximide: acts synergystically with other ingredients (such as pyrethrins and pyrethroids) to better repel and kill a variety of ectoparasites
• Permethrin: a pyrethroid; (see beta-cyfluthrin)
• Phenothrin: a pyrethroid; (see beta-cyfluthrin)
• Piperazine: a benzene sulfonamide; a dewormer used to treat roundworms
• Piperonyl butoxide: acts synergystically with other ingredients (such as pyrethrins and pyrethroids) to better repel and kill a variety of ectoparasites
• Praziquantel: an isoquinolone; a dewormer: kills some intestinal worms (including tapeworms and flukes, which are not affected by many other dewormers)
• Pyrantel: a tetrahydropyrimidine; a dewormer: disrupts the nervous system of some gastrointestinal worms (excluding tapeworms), causing paralysis of these parasites, which then allows the host body to rid them
• Pyrethrins: pesticide class that cause paralysis and death of a variety of ectoparasites; also has repellent activity; less toxic yet not always as effective as their synthetic cousins, pyrethroids
• Pyriproxyfen: an insect growth regulator; an immature insect hormone that interrupts flea development
• Sarolaner: an isoxazoline; (see afoxolaner)
• Selamectin: a macrolide (macrocyclic lactone); (see ivermectin); unlike other macrolides, selamectin is safe to administer to dogs with MDR-1 gene abnormalities (such as collies); does not control as many intestinal worms in dogs as other macrolides
• (S)-methoprene: an insect growth regulator; (see pyriproxyfen)
• Spinetoram: a spinosyn; affects the nervous system of insects (similar to neonicotinoids); low risk of toxicity in pets
• Spinosad: a spinosyn; (see spinetoram)
• Tetrachlorvinphos: an organophosphate; (see chlorpyriphos)
• Tetramethrin: a pyrethroid; (see beta-cyfluthrin)

Even this dog was getting a bit fatigued when reviewing that tedious ingredients list! Alas, you can always store it as a future reference. But now for some more exciting things…

What are the Pros and Cons of Product Administration: the Good, the Bad, and the Ugly?

• Topical: Most topical medications are stored in your pet’s hair follicles and oil glands (sebaceous glands), spreading along your pet’s skin to provide parasite protections. For this reason, washing your pet too frequently may strip his or her natural oils… and the topical preventive along with them. Therefore, avoid bathing your pet or allowing him or her to swim several days before and after applying a topical product. Most topical applications (known as spot-on types) should be applied directly to your pet’s skin (at an area where your pet can’t reach to lick it off) rather than on the hair; this can cause a temporary greasy spot that some owners do not like. Some topical products (such as those containing pyrethroids) can cause a burning or tingling sensation when applied to your pet’s skin, and your pet may attempt to bite or scratch the area, resulting in secondary skin trauma. Topical applications may be perfect for some cat owners who struggle with administering oral medications to their iron-jawed kitties.
• Collars: Collars work similarly to other topical applications, yet there is not usually a lingering greasy residue. With most collar brands, your pet should not bathe or swim while wearing it, as water can reduce the product’s lifespan and efficacy. Additionally, some collars may cause mild redness or hair loss around the neck of your dog or cat, which is usually temporary and resolves shortly after the collar is removed. To be on the safe side, be sure to choose a break-away style collar that your pet can remove with a bit of force if he or she becomes trapped should the collar be caught on something outdoors.
• Oral: Oral meds, especially flavored chewy products, are a great option for your food-motivated doggie and kitty, who think their monthly flea, tick, or heartworm preventive is a yummy treat! Yet some cats do not tolerate oral medications well, so their owners may opt for topical or collar products instead. However, some oral formulations can cause nausea and vomiting in some pets. Thus, many are recommended to be given with food to minimize side effects; this may also improve the absorption and efficacy of some products. Be sure to monitor your dog or cat closely for at least a few hours after giving him or her an oral preventive to ensure that it is not vomited up, leaving your pet unprotected for the upcoming month(s). Furthermore, some flavored products should be avoided in animals with particular food allergies in favor of a topical or injectable product instead.
• Injectable: Some of the ingredients discussed above can be used as injectable formulations (such as ivermectin, commonly injected in livestock for gastrointestinal parasite control or even to dogs and cats for the treatment of some severe mite infestations). However, for all intents and purposes of this article, the injectable formula of interest is ProHeart®6, an injectable heartworm prevention for dogs administered by your veterinarian every 6 months (i.e. twice annually), making this product very convenient for some pet owners. However, it can make for a more expensive choice up-front and does not control as many intestinal parasites as other formulations. (similar product: ProHeart® SR-12)

What about common over-the-counter products?

I am aware that over-the-counter (OTC) parasite preventives are convenient and oftentimes more affordable than those obtained from your vet’s office. Some OTC products may very well be safe and effective. However, it’s oftentimes true that “you get what you pay for,” and this statement holds true for many other brands of OTC merchandise.

For the most part, I tend to recommend products purchased at a vet clinic since these items have been exhaustively studied to ensure efficacy and safety when dosed appropriately. Such veterinary product manufacturers in good repute include Bayer, Ceva, Elanco (previously Novartis), Merck, Merial, Virbac, and Zoetis (previously Pfizer).

Many OTC options may include the same ingredients as those made by the veterinary pharmaceutical companies just mentioned. However, the amount or concentration of ingredients may greatly differ from the carefully measured and thoroughly studied amounts contained in products offered only by your veterinarian. Some over-the-counter merchandise may contain the same ingredients as a safer brand… but at a a dangerously high level. Some products may lack quality control studies that ensure long-lasting efficacy. That being said, use caution if you insist on buying common OTC brands for flea and tick control, a smattering of which include:

• Adams™: This brand offers a variety of formulations, including spot-on topical treatments, collars, dips, and shampoos to prevent fleas and ticks and to repel mosquitoes. However, these products often contain organophosphates, which can cause severe neurologic toxicity if administered at an incorrect dosage.
• Bio Spot Active Care™: Spot-on treatments, sprays, collars, and shampoos are available from Bio Spot™, containing a variety of ingredients intended to prevent fleas, ticks, and lice while also repelling mosquitoes. Some products, such as the flea and tick collars, contain organophosphates, which may not be as effective in collar form and can also be toxic, especially to cats.
• Hartz®: These flea and tick collars and spot-on topical applications typically contain a high concentration of pyrethroid and/or organophosphate ingredients. In high doses, these chemicals can be very dangerous and even deadly to dogs and cats, causing tremors, seizures, collapse, and death. I personally have witnessed several cats suffer the toxic effects of such products, and I typically advise pet owners to avoid them. If you suspect your cat is suffering the toxic effects of such medications, contact the ASPCA’s Animal Poison Control Center at 1-888-426-4435 immediately (fees may apply).
• PetArmor®: Many products by this company boast that they’re a fierce rival to Frontline®, containing many of the same active ingredients such as fipronil and etofenoprox. While these active ingredients are indeed the same as found in certain Frontline® brand products and are even the same amounts, the inactive ingredients are vastly different and may contain chemicals harmful to your pets. Don’t be fooled by lookalikes.
• Sergeant’s®: As with other brands, inactive ingredient composition may be of concern. Additionally, this company’s Green brand of products with “natural” ingredients may lack efficacy and toxicity data. (The difficult-to-watch video below displays the effects of toxicity in cats that have reportedly been administered such products.)
• Sentry®: I’m starting to sound a bit like a broken record here, but several options by Sentry® also promote themselves as Frontline® equivalents, but their inactive ingredients are unlikely to be the same and may be harmful to pets.

What about “Natural” and other Alternatives?

Just because a product is natural or herbal does not mean that it’s safer; the same goes for other alternative products. The opposite may instead be true as many of these products lack data concerning safety or toxicity information as well as studies on their efficacy. Therefore, some of these ingredients may be harmful to pets (especially cats) if administered in improper dosages. Overall, it is best to avoid use of these products in your canine and feline companions:

• DDT: a chlorinated hydrocarbon (organochlorine); a pesticide that is banned in many countries due to its controversial environmental ramifications; avoid use in your pets
• DEET: used in some insect repellent formulations for humans; should not be administered to dogs or cats
• D-Limonene: used as a repellent against mosquitoes and other insects; can be toxic to pets in high doses, so be wary of products including this natural ingredient
• Picardin: lemon eucalyptus oil used in some insect repellent formulations for humans; should not be administered to dogs or cats (please not that some natural essential oils that may be safe to humans can be especially toxic to cats due to metabolic differences between us and felines)

I am also often asked by environmentally-conscious pet owners about the potential toxic effects of flea and tick products. These clients want to protect their pets’ health by avoiding chemicals. I understand where they’re coming from. However, a misconception regarding the word “chemical” is that all chemicals, especially synthetic ones, are harmful to dogs, cats, and humans. This just isn’t true. The majority of parasite preventives purchased at your vet’s office contain ingredients that only affect ticks and mites, insects (such as fleas), as well as heartworms and intestinal worms. Due to the species differences in us mammals (dogs, cats, and humans), our cells are not damaged by these ingredients that target only parasitic cells instead. (An exception is organophosphates found in some over-the-counter varieties, which can be harmful to both pets and humans.) Want to really protect your pet’s health? Focus instead on minimizing diseases such as heartworm infection, tick-borne illnesses (like Lyme disease, Rocky Mountain Spotted Fever, and Cytauxzoonosis), and complications from fleas (such as dermatitis, Mycoplasmosis, cat scratch fever, and possibly fatal anemia caused by heavy infestations). Show your dogs and cats how much you care by providing them with a veterinary-approved parasite preventive used year-round.

What about garlic? No. Repeat after me: No. Nooooo!!!! Despite the old wives’ tale that feeding garlic to your pet will help repel fleas and other insects, consuming garlic (and similar foods like onions and shallots) can be extremely dangerous and even deadly to dogs and cats. Garlic ingestion causes the destruction of red blood cells in dogs and cats, a process called hemolysis, which can result in perilously low red cell count (or anemia). This impairs with the body’s ability to circulate oxygen and other vital nutrients to vital organs and can sometimes result in your pet’s death. Just… no!

Other “backyard treatments” I’ve been asked about? Dipping pets in motor oil or gasoline to kill fleas, ticks, and mites and feeding pets meat grease or vegetable oil to rid them of intestinal worms. These do not work and can be extremely dangerous to dogs and cats. Once again… just say NO!

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For more information on human foods toxic to dogs and cats, read The Meowing Vet’s article: Don’t You Dare Eat That!

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Now the fun stuff: The Meowing Vet’s Flea, Tick, and Heartworm Product Comparison Charts!

Which veterinary preventive offers protection against the parasites of which I’m most concerned, and which product is available in a formulation I know is easiest to administer to my pet?

Download your charts now!

 

Canine Product Chart

CLICK TO DOWNLOAD: The Meowing Vet – Flea, Tick, and Heartworm Product Chart – Dog

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Feline Product Chart

CLICK TO DOWNLOAD: The Meowing Vet – Flea, Tick, and Heartworm Product Chart – Cat

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To view these PDF files, you may need to install the latest version of Adobe Acrobat Reader DC.

Edited on May 8, 2017; CORRECTION: Revolution® and Stronghold® for dogs does NOT control roundworms and hookworms. Revolution® and Stronghold® for cats does in fact control both roundworms and hookworms in felines. The downloadable chart for canines has been updated to reflect this correction. Edited on August 7, 2017; ADDITION: Advantage Multi® is called Advocate® in some markets.

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For additional information on making smart and safe choices when it comes to your pet’s flea and tick prevention, which includes NEVER administering your cat a preventive that is intended to be applied only to dogs, visit the American Veterinary Medical Association’s website. Check out the AVMA’s safety video below.

Congratulations on being an amazingly informed pet owner! Now that you’ve downloaded The Meowing Vet‘s snazzy charts comparing common flea, tick, and heartworm preventives, you have the knowledge and tools to choose the perfect product to protect your dog or cat. If you have further questions, it’s always a good idea to speak with your vet.

– Maranda Elswick, DVM

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