Practicing natural flea and tick prevention for your dog is challenging. So what do you do when going natural just isn’t working? And you’ve got a flea or tick infestation beyond what you and your dog can handle. All that scratching … and you both just want relief … FAST!
You might want to throw in the towel and turn to the heavy hitters … pharmaceutical flea and tick prevention. But don’t feel defeated. Here’s what you need to help you wade through all the options to find the safest flea and tick prevention for dogs.
We’ve ranked the different types of flea and tick preventives in reverse order of safety … from riskiest to safest.
#1 Definitely Not Safe – Oral Flea And Tick Preventatives
These are the worst offenders and most dangerous to use on your dog. They’re taken orally, usually as a tasty chew for your dog. These drugs contain isoxazolines. And they’re usually only available by prescription.
Many of these meds contain a class of ingredients called isoxazolines. They’re non-competitive GABA (gamma-aminobutyric acid) receptor antagonists. This means they bind to chloride channels inside the flea or tick. In plainer English, they block nerve signals … which paralyzes and kills the bugs.
How Oral Flea And Tick Preventatives Work
When you give your dog isoxazolines, they work systemically. This means they’re absorbed into his blood and they affect the entire body. When fleas and ticks feast on your dog’s blood, they eat the chemicals … and become paralyzed and die.
The Food and Drug Administration (FDA) has alerted pet owners and veterinarians that there’s potential for neurological damage when using drugs in the isoxazoline class. The reactions include muscle tremors, impaired movement, lack of coordination and seizures.
After reviewing as many brands of oral chews and tablets as we could find, here’s a list of active ingredients you’ll want to watch for on the label.
Active Ingredients In Oral Flea And Tick Meds
The first list below are chemicals used solely to prevent flea and tick bites and infestations. They’re potent and dangerous enough. They include acaricides that are pesticides poisonous to ticks and mites. Ectoparasiticides are to treat external parasites like fleas, ticks, lice, mites and flies.
The second list shows antiparasitic chemicals also known as anthelmintics. This means they expel parasites like worms. These are dewormers added to the flea and tick products. You should avoid this combination of drugs because it increases the risk to your dog. Flea and tick medications are often given for 8 months … or longer if you’re in a warm climate. But you should never treat your dog for worms unless he has them. And if he does, there’s no need to give a dewormer for the entire flea season.
So if you see ingredients from the first list AND the second list, you’re getting unnecessary and harsh dewormers. This is on top of risky flea and tick medications. Some claim to prevent as many as 6 different insects and worms … including fleas, ticks, lice, worms and heartworm. This is a lot of unnecessary medication and can lead to some pretty serious side effects … especially when your dog doesn’t need the extra meds!
Ingredients Against Fleas And Ticks
- Afoxalaner – a member of the isoxazoline family
- Fluralaner – for systemic use and also a member of the isoxazoline family; it is the single active ingredient found in one brand of chews that lasts for 12 weeks!
- Sarolaner – an acaricide and insecticide also belonging to the isoxazoline family
- Lotilaner – an ectoparasiticide belonging to the isoxazoline family, with a 1 month duration
- Spinosad – made from soil bacteria that is toxic to insects and found in garden insect spray
- Lufenuron – controls flea infestations by preventing the hatching of eggs, and prevents the flea shell from developing
Unnecessary De-Wormers Often Included
- Milbemycin oxyme – used as a broad spectrum antiparasitic for heartworm, and internal parasites including hookworm and roundworm
- Moxidectin – an anti-parasitic to control heartworm and intestinal parasites
- Pyrantel – an anthelmintic, or dewormer
- Praziquantel – an anthelmintic used for parasites like tapeworms
The Problem With Oral Flea And Tick Meds
The problem with poisoning fleas and ticks is that you’ll also poison the host … and that’s your dog! So If you want to find the safest oral flea treatment for dogs … The answer is, there’s no such thing.
The theory behind isoxazolines is that your dog is a lot larger than a flea … so they assume a little bit of poison won’t hurt him. And that might sometimes be true. But what happens if you give your dog a small amount of this poison every month for years? The manufacturer (Zoetis in one study) doesn’t actually know what happens … because safety studies were only done for 3 months.
Side Effects Of Oral Flea And Tick Meds
But dog owners have reported some pretty serious side effects. They’re often neurological in nature, like seizures. That’s because most of these products kill the pests by attacking the nervous system and paralyzing them. Side effects from these drugs include:
- Tremors
- Seizures
- Ataxia – stumbling, falling, uncoordination
- Vomiting
- Diarrhea
- Loss of appetite
- Skin irritations
- Lethargy
These symptoms show that dogs are being poisoned along with their pests. They’re suffering the same neurological issues that kill the fleas and ticks. So every dog is at risk. And you only need look through social media at dedicated pages where heartbroken owners describe the seizures their dogs suffered … before they died.
Even the inactive ingredients in chews are undesirable. They may not be listed, but can include things like “natural” flavors that aren’t natural, starches, sugars and preservatives … to name a few.
#2 Pretty Unsafe: Flea And Tick Collars
The second riskiest category is impregnated flea and tick collars that your dog wears all day and all night for as long as 8 months. So they’re right under your dog’s nose all the time. The absorption of chemicals is through the skin. And unlike oral flea and tick preventives, your dog isn’t supposed to eat these. But accidents happen. A lot of them, according to reports from the Environmental Protection Agency (EPA).
Even if your dog doesn’t slip out of his collar and chew on it, another dog at the park or in the family might. It can easily come off and become a chew toy. And that’s a highly toxic chew toy. Just read about the ingredients that follow. Unlike oral flea medications, these collars might not need a prescription. That means a household could also have several on hand that could easily fall into the wrong paws.
The EPA shows that from January 2012 through mid-June 2020, it received incident reports about just one brand … Seresto collars … documenting 1,698 pet deaths. And more than 73,000 injuries rated as minor, moderate or major. There were almost 1,000 reports of harm to humans. That includes a 12-year-old boy who had seizures and vomiting after sharing his bed with a dog wearing the collar.The product registration document filed with the EPA warns that children should avoid contact and shouldn’t play with the collars.
Active Ingredients In Flea And Tick Collars
- Flumethrin – a synthetic pyrethroid, in the same category as insecticides like permethrin. Pyrethroids paralyze the insects’ nervous systems.
- Pyrethroid – a synthetic chemical class of insecticides isolated from the chrysanthemum. Permethrin is one of those insecticides. Permethrin poisons the central nervous system.
- Deltamethrin – another synthetic version of pyrethrin from the chrysanthemum. It’s an insecticide used in malaria control and as a coating on mosquito nets.
- Imidaclooprid – it’s a neonicotinoid insecticide used for crop protection and in pet insecticides.
- Tetrachlorvinphos – it’s an insecticide. It’s used as a medication, insecticide and nerve agent as a weapon. Used as an oral larvicide in livestock and against flies in dairy. Kills fleas, ticks, lice, chiggers, mites, spiders and wasps.
- Methoprene – slow acting insecticide that interferes with the growth cycle of an insect to prevent it from maturing and reproducing.
- Pyriproxyfen – used in pesticides, it mimics a natural hormone in insects and prevents eggs from hatching. It’s used to control fleas, cockroaches, ticks, ants, carpet beetles and mosquitoes.
How Flea And Tick Collars Work
The chemicals in these collars release into the area around your dog and into his skin. Then the chemical circulates through the bloodstream. When a flea or tick draws blood from your dog it’s infected with the chemical and dies. This takes place over several months while your dog wears the collar.
These collars are for external use only … but how does your dog know that? He cleans himself by licking his skin and fur. He’ll easily ingest the collar’s pesticides that disperse onto his fur and skin over several months … through his whole body.
Your dog is a mammal and they tolerate pyrethroid insecticides such as flumethrin much better than insects like fleas. For insects the toxicity is 1,000 times higher. But keep in mind a flea or tick only bites once. Your dog has constant exposure through his skin and breathing, or he may have open wounds … so the impact can be far more serious.
Side Effects Of Flea And Tick Collars
The chemicals used in these collars are neurotoxins, endocrine disruptors and immunosuppressants. They can cause these signs and symptoms …
- Nausea, vomiting
- Seizures
- Diarrhea
- Salivation
- Tremors and Convulsions
- Hyperactivity and hypersensitivity to touch or sound
- Inflammation
- Kidney and liver damage
- Organ toxicity
- Disrupts proper functioning of antioxidants
- Thyroid damage
- Abortions and birth defects
Beware Fake Flea Collars
Flea and tick prevention is big business so it’s no surprise that there are counterfeit products vying for a piece of the pie.
The well-known Seresto flea collar brought in $300 million in sales in 2019. This success attracts plenty of knock-offs. You need to watch for fake name brand collars and off-brands as well. The bogus collars might not protect your pet from fleas and ticks. In fact, the ingredients might be even more harmful than chemicals in the real thing. They can cause severe illness as well as burns. The genuine manufacturers claim that some of the reports of injuries to pets are due to the fake collars.
If buying a Seresto collar, get it from a reputable source, like a vet supply company. Don’t buy it from an unknown online source or even Amazon or E-Bay! You can go through the Bayer website, the manufacturer, to get a list of local and online authorized retailers.
If you believe you have a fake collar, you need to call Bayer directly. Give them the lot number and serial number of the product and find out if they made it.
Seresto In The News
In 2021, the US House Subcommittee on Economic and Consumer Policy called on Elanco, manufacturer of the Seresto collar, to temporarily recall its collar. The company refused.
After a 16-month investigation, the committee released a 24-page report in June 2022. It’s titled: Seresto Flea and Tick Collars: Examining Why A Product Linked To More than 2,500 Pet Deaths Remains On The Market. Reported numbers from June 2020 have been updated to 98,000 (up from 75,000) incidents and 2,500 (up from 1,700) pet deaths.
The subcommittee made three main recommendations:
- Recall Seresto collars and begin canceling the collar’s registration
- Strengthen the EPA’s scientific review process
- Improve incident data collection
In a statement a year ago, Elanco noted more than 25 million collars were sold in the US. The incident report rate for all adverse events was .3%. The simple math is that 750,000 animals had some type of reaction to the Seresto collar since 2012. So even a low percentage of problems is a lot of harmed animals
#3 Safer But Still Risky
There are two types of products in this category.
I. Spot-On Flea And Tick Prevention
The third highest risk category is the pharmaceutical topical treatments commonly called spot-ons. That’s because they’re applied to your dog by dropping the medication onto spots along your dog’s back. In general, you’ll want to use the ones with the fewest ingredients. Just like the oral preventives, avoid spot-ons with extra ingredients that cover a range of pests. If your dog isn’t infested with several pests he doesn’t need the additional treatment and the toxins that go with it.
Active Ingredients In Spot-Ons
- Fipronil is a broad-spectrum insecticide that belongs to the phenylpyrazole chemical family. It disrupts the insect’s central nervous system and causes hyperexcitation of its nerves and muscles.
- Imidacloprid – a systemic insecticide that acts as an insect neurotoxin to attack the central nervous system of sucking pests like fleas. It’s also toxic to honeybees and mimics the effects of nicotine on insects.
- Permethrin – as described in #2. Also used to treat lice.
- Pyriproxyfen – as described in #2.
- Moxidectin – as described in #1.
- Dinotefuran – in a class of neuro-active insecticides known as neonicotinoids that are chemically similar to nicotine. It does not require ingestion by the insect to be effective.
- (S)-methoprene – an insecticide that stops growth and development. It prevents egg-laying and hatching, so pests don’t reproduce.
- Selamectin – an antiparasitic and antihelminthic insecticide used on dogs to treat heartworms, fleas, ear mites, sarcoptic mange. It’s a dewormer and an insecticide.
How Spot-On Flea And Tick Prevention Works
Topical flea and tick preventives get applied as liquid along a dog’s back, usually between the shoulder blades. They’re absorbed into the skin, then chemicals circulate into the bloodstream and travel into the sebaceous glands. The active ingredient releases and moves through the glands that lubricate a dog’s coat with oil. When an insect draws blood from your dog the chemical infects it and it dies.
Like all products given to your dog by mouth or bloodstream, they remain in your dog’s system. Some products are longer lasting in your dog than others. Shorter duration is a good thing. That means it leaves your dog’s system more quickly … and you may not need to re-apply it.
But your dog licks himself to clean himself. And the chemicals circulate through his body. So even though application was on his back, no matter where he licks, the chemicals get secreted through his skin throughout his body.
Side Effects Of Spot-Ons
The EPA’s Pesticide Division, found that fipronil enters the body and can be contained in the fat, organs, urine and feces of dogs. The EPA also found that most of the reactions to fipronil involved systemic as well as application site, digestive, neurological and behavioral disorders. The most common clinical signs were:
- Skin reactions like hair loss, itching, and redness
- Dermatitis
- Sores
- Irritation
- Hair changes at the application site
- Neurological issues like uncoordinated movement
- Lethargy
Brief exposure to (S)-methoprene can cause mild or moderate skin irritation in humans. Higher doses in dogs can cause:
- Vomiting
- Dilated pupils
- Changes in behavior
- Changes in breathing
- Changes in muscle control
Imidacloprid has caused skin irritation in pet owners after applying spot-on products to their animals.
PRO TIP
If you’ve chosen to use a medicated flea and tick spot-on, you may not need the full dose. You can give your dog just a drop or 2 of the spot-on treatment. Start with a little to see if you are getting results. You can always increase the dosage.