Bravecto, Nexgard And Simparica: Are These Chewable Flea And Tick Preventives Safe?

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Post At A Glance

Like every dog owner, you want to avoid fleas on your dog and in your home. And you don’t want your dog picking up ticks and risking tick-borne disease.

Wouldn’t it be convenient to just give your dog a tasty chew every month or 3 months to protect her from fleas and ticks?

Well, recently, some new flea and tick prevention products for dogs let do just that.

Great! Problem solved …

… or is it?

No, it’s not! If you got excited about the idea of a longer term chewable flea and tick medicine … hold your horses right now!

Don’t jump on these drugs. They have a dark side. Keep reading to learn about their sometimes deadly side effects.

What Are The New Drugs?

There are three drugs in the category of chewable flea and tick preventives: Nexgard, Bravecto and Simparica.

Nexgard (active ingredient afoxolaner) and Bravecto (fluralaner) were approved in the US in late 2013 and early 2014. Simparica (sarolaner) was just introduced in March 2016.

The dosing schedules are once a month for Nexgard and Simparica and once every three months for Bravecto.

How The Preventives Work

These flea treatments are oral medications. The drugs come in a soft chew that your dog can eat like a treat. After your dog takes the chew, the drugs circulate in the blood, and when a flea or tick bites your dog, it’s exposed to the chemical. This exposure will kill fleas and ticks.

All three drugs are pesticides that work by attacking the nervous system of the fleas and ticks, causing death. The statements below describing the Mode of Action of these drugs are from the manufacturers’ Prescribing Information.

Nexgard (afoxolaner)

Cutout of Nexgard's manufacturer mode of action

Bravecto (fluralaner)

Cutout of Bravecto's manufacturer mode of action

Simparica (sarolaner)

Cutout of Simparica's manufacturer mode of action

So, these chewable drugs work by destroying the insects’ nervous systems. If it’s deadly for fleas and ticks, how might it affect a dog? It remains in your dog’s bloodstream for extended periods of time, after all.

And, once your dog takes one of these drugs, if she has any side effects, you can’t remove the drug from her body.

First Stop, The FDA

Every drug has side effects and I wanted to find out what reactions dogs might have had to these meds.  My first stop for this type of information is usually the US Food and Drug Administration (FDA). The FDA collects Adverse Drug Event Reports on its website.

But I was out of luck … because the FDA has made it near-impossible to find these ADE reports on their database.

Luckily, however, I came across some useful information, thanks to veterinarian Dr Elizabeth Carney.

Back in November 2014, when Nexgard and Bravecto were first introduced, Dr Carney wrote about the new chewable drugs on her blog. And then she started receiving comments from people whose dogs were already experiencing side effects after taking these preventives. She wanted to find out more.

So she filed a Freedom of Information Act (FOIA) request to obtain the reports and received a number of ADEs for Nexgard and Bravecto. Dr Carney has generously made these reports available on her website, so I took a look at them.

ADE Reports For Nexgard And Bravecto

Here s the FDA’s summary of the ADE reports received for Nexgard and Bravecto from January to March 2016. (When I read the summary below, I did find myself wondering who would give Bravecto to a porcupine!)

FDA’s summary of the ADE reports received for Nexgard and Bravecto from January to March 2016

Dr Carney didn’t get any reports for Simparica as it was too new at the time.

There are specific ADE reports for Nexgard and Bravecto for the period January through March 2016. The results are very similar for both drugs.

Vomiting, lethargy and diarrhea are the most common side effects reported. Seizures are quite high on both lists, with 22 each for both Nexgard and Bravecto for the first quarter of 2016. Nine deaths are reported for each drug for the same period.  For Nexgard, five of the nine deaths were by euthanasia.

Nexgard (afoxolaner)

FDA’s summary of the ADE reports received for Nexgard from January to March 2016

Bravecto (fluralaner)

FDA’s summary of the ADE reports received for Bravecto from January to March 2016

More Reports From Dog Owners

Facebook is another source of information about the side effects of these chewable drugs. These group pages contain many tragic stories from dog owners who believe their dogs have been harmed by these pest preventives.

And these groups have tens of thousands of members … so the risks are real!

Does Bravecto Kill Dogs?

Does Nexgard Kill Dogs?

Bravecto Nexgard Comfortis Simparica Trifexis & others Do They Kill Dogs?

Some of the posts are fascinating as well as alarming. One poster reports finding dead ticks on her dog as long as 12 months after his last dose of Bravecto … suggesting that’s how long it stays in your dog’s bloodstream!

So again, a reminder that if your dog experiences an adverse effect … you can’t just stop using it and expect your dog to return to normal!

More Information About Simparica

Simparica hasn’t been out as long … so there’s less information.

As you saw from the Prescribing Information above, this drug works just like Bravecto and Nexgard … it destroys flea and tick nervous systems. So it’s very likely that the adverse effects of this chewable drug will be similar to the other two drugs.

The manufacturer’s website provides this warning about “neurologic signs” the drug may cause in your dog:

Simparica may cause neurologic signs such as tremors, unsteadiness and/or seizures in dogs with or without a history of neurologic disorders. 

If you want to see the kind of effect Simparica can have on your dog, click on this video link. I warn you, though … the video is very distressing to watch.

It shows a dog having a really long seizure after taking Simparica. This poor dog died a few months later because of his seizures.

Vets Agree

Dr Carney, who obtained these reports from the FDA, told us that she has personally decided not to use these chewable drugs for her own dog, nor will she prescribe them to her clients.

Many other holistic vets are speaking out about the dangers of these long-lasting preventive products too. Check out this recent Facebook post by Dr Josie Beug:

flea and tick preventives

Even The FDA Agrees!

So I hope I got the message across.

Please don’t sacrifice your dog’s health for these “convenient” chewable options. That’s a really dangerous trade-off.

You can avoid harmful pest preventives for your dog. There are lots of natural, safe options. You might have to work a little harder … but your dog is worth the effort!


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