What flea and tick medicine is killing dogs

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Fleas and ticks can get on your pet’s nerves. But apparently so might some medications to get rid of these pests.

The U.S. Food and Drug Administration (FDA) has issued a warning that medications in the isoxazoline class such as Bravecto, Credelio, Nexgard and Simparica may do more than just combat flea or tick infestations. These medications have the potential of causing seizures, ataxia, muscle tremors, or other neurological problems in your pets. Ataxia is a condition in which your pets can’t control their muscle movements and thus may have trouble walking, balancing, or speaking. Of course, you may not necessarily be able to tell if your pet is having difficulty speaking. But the FDA warning means that you should be on the lookout for any struggles that your pet may be having after taking these medications.

It is not a complete surprise that these medications may affect your pet’s nervous system. After, these medications act by messing with the nervous systems of fleas and ticks. Your pet, typically a dog or cat since alpacas are not common household pets, will first munch on the medication. The medication then gets into your pet’s bloodstream. There the medication may enter any flea or tick that is actively feeding on your pet’s blood.

That’s where the fun begins for the fleas and ticks. As with humans, nerves in fleas and ticks acts like wires conducting electrical signals that control movement and other functions. These electric signals normally jump from nerve to nerve via neurotransmitters such as gamma-aminobutyric acid (GABA) and glutamate. However, the medication can interfere with the actions of these neurotransmitters, impeding the transmission of these electrical signals. This can then paralyze and kill the fleas and ticks, in essence short-circuiting their nervous systems. Dead fleas and ticks also can’t lay eggs and reproduce. 

With this mechanism of action, it shouldn’t be a complete surprise that the medications may also screw with your pet’s nervous system. But before you freak out about the medication paralyzing and killing your pets, keep in mind that the medications are still FDA-approved for use in pets, assuming that your pet is not a giant flea. Fleas and ticks are thankfully much smaller than dogs and cats. So they tend to be more susceptible to smaller amounts of the medications. They also have different anatomy and physiology.

Note that the FDA didn’t say how common such side effects in dogs and cats may be. The FDA only issued a warning and asked manufacturers to include the warning on their labels. Currently, the risk nay not be high since the FDA did not advise against using the medications for your dogs and cats.

So, for you fleas and ticks out there hoping that the FDA would pull these medications from the market, sorry that’s not going to happen. If you are a human, this news may not change your flea and tick control methods but don’t use these medications on your pet without guidance from a veterinarian. Keep your veterinarian informed about any changes in your dog’s or cat’s behavior while on these medications. If you are a veterinarian, make sure that pet owners are aware of these potential side effects and discuss flea and tick control options if they are concerned. And if you are a dog or cat, woof, woof, woof, and meow, meow, meow.

I am a writer, journalist, professor, systems modeler, computational and digital health expert, medical doctor, avocado-eater, and entrepreneur, not always in that order. Currently, I am a Professor of Health Policy and Management at the City University of New York (CUNY) School of Public Health, Executive Director of PHICOR (@PHICORteam) and Center for Advanced Technology and Communication in Health (CATCH), and founder and CEO of Symsilico. My previous positions include serving as Professor By Courtesy at the Johns Hopkins Carey Business School, Executive Director of the Global Obesity Prevention Center (GOPC) at Johns Hopkins University, Associate Professor of International Health at the Johns Hopkins Bloomberg School of Public Health, Associate Professor of Medicine and Biomedical Informatics at the University of Pittsburgh, and Senior Manager at Quintiles Transnational, working in biotechnology equity research at Montgomery Securities, and co-founding a biotechnology/bioinformatics company. My work has included developing computer approaches, models, and tools to help health and healthcare decision makers in all continents (except for Antarctica). This has included serving as the Principal Investigator of research grants from a wide variety of sponsors such as the National Institutes of Health (NIH), Agency for Healthcare Research and Quality (AHRQ), National Science Foundation (NSF), the Centers for Disease Control and Prevention (CDC), UNICEF, USAID, the Bill and Melinda Gates Foundation, and the Global Fund. I have authored over 250 scientific publications and three books. I've also written articles for The New York Times, Time, The Guardian, The HuffPost, STAT, and the MIT Technology Review and others. My work and expertise have appeared in leading media outlets such as The New York Times, ABC, USA Today, Good Morning America, Tamron Hall Show, BBC, The Los Angeles Times, Newsweek, CBS News, Businessweek, U.S. News and World Report, Bloomberg News, Reuters, National Public Radio (NPR), National Geographic, MSN, and PBS. Follow me on Twitter (@bruce_y_lee) but don’t ask me if I know martial arts.

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Finding an effective, safe flea treatment for your dog is an important pet parent task. Here’s what you need to know to make sure your dog gets the flea protection they need with as little risk to their health as possible.

What to Consider When Picking the Safest Flea Treatment for Dogs

Keep in mind that no two pets are the same. Therefore, a product that’s commonly considered to be safe flea and tick prevention for dogs may be a great option for one animal and a mistake for another. Factors to consider include:

• Age: Flea treatments must be age-appropriate; many are not made for young puppies. Look at the product’s label for this information.

• Breed: Coat type may influence your decision. Thicker coats may be difficult for topical treatments.

• Your pet’s health history: Other medications or supplements that you give, concurrent health conditions, and previous reactions to flea and tick preventatives should be taken into account. For example, neurologic problems have been seen in dogs when high doses of ivermectin (heartworm prevention ingredient) are given in conjunction with spinosad, a flea preventative ingredient.

• Your pet’s lifestyle: The presence of children and other pets (especially cats) in the household and your pet’s daily activities/exposure to the outdoors are important details.

• Where you live: Which parasites are common in your area? Is resistance to certain preventatives a concern?

Your veterinarian will take these details into account and help you decide which flea and tick preventative is best for your dog.

Many of the safest and most effective options require a veterinarian’s prescription, so it makes sense to have this discussion sooner rather than later.

Types of Safe Flea Treatments for Dogs

Veterinarians typically recommend dog flea and tick collars, topical flea and tick treatments, or oral flea and tick medications (sometimes in combination) to fully protect their patients. Here are a few of the safest flea treatments for dogs on the market today and some of their pros and cons.

Dog Flea and Tick Collars

Under many circumstances, newer dog flea collars are safe options for flea and tick control (unlike older collars, which were largely ineffective). The Seresto collar is a very popular option right now.

It uses flumethrin and imidacloprid to kill fleas at multiple stages of development as well as ticks. The collar’s effectiveness lasts for 8 months (as long as you minimize its exposure to water), so it is a convenient alternative to monthly prevention treatments.

However, if you have small children in your home, do not let them play with a Seresto collar or the included reflector clips. All flea and tick collars tend to leave traces of the chemicals that make them effective around the dog’s environment and on your pet, so this may be a concern with young children who tend to put everything in their mouths.

Some dogs have had local skin reactions to the collar that have resolved when it was removed. Seresto’s product insert also states, “Consult your veterinarian before using this product on debilitated, aged, breeding, pregnant or nursing animals.” This holds true for all flea and tick preventatives.

Topical Flea and Tick Treatments for Dogs

Several safe flea treatments for dogs are available as topical (or spot-on) treatments, and many offer protection against far more than just fleas.

For example, Advantage Multi is a prescription treatment that uses the active ingredients imidacloprid and moxidectin to kill heartworms, hookworms, whipworms, roundworms, sarcoptic mange mites and fleas. It doesn’t kill ticks, however, and dogs should not be allowed to lick the application site for at least 30 minutes to avoid potentially serious side effects.

Frontline Plus is an OTC product that uses fipronil and (S)-methoprene to attack fleas and ticks at every life stage. It also eliminates chewing lice and helps to control sarcoptic mange infestations. While it shouldn’t be ingested, a few surreptitious licks by your dog won’t cause much in the way of problems.

As is the case with flea and tick collars, if you’re unable to keep your pet away from small children or animals who may come into direct contact with the medication before it has dried or absorbed into your pet’s skin, a topical treatment might not be the ideal solution.

If you have cats in your home, you will want to talk to a veterinarian before choosing a topical flea and tick medication for your dog. Some utilize ingredients like pyrethrin or permethrin, which are incredibly toxic to cats.

Ideally, you should wait several days after application to bathe a dog. Topical treatments generally need to be applied monthly.

Oral Flea and Tick Medications for Dogs

There are several oral prescription flea and tick medications that are considered to be quite safe for dogs. These preventatives come in pill and chew forms. Your vet can help you find the right one for your pup’s age.

Trifexis employs spinosad and milbemycin oxime to keep dogs protected from heartworms and intestinal parasites as well as fleas, but it does not work against ticks. Your vet will need to prescribe this treatment.

Bravecto chews (it also comes as a topical) offer protection from fleas and ticks for 8-12 weeks per dose. It uses the active ingredient fluralaner, which kills adult fleas and ticks. Bravecto also requires a prescription from your veterinarian.

Oral flea and tick medications are great for households with small children or other small pets who may be in danger of coming into contact with the chemical residue from flea collars or topical medications.

The most common side effect reported for prescription oral flea medications is vomiting.

No medication is without the risk of side effects, but leaving parasites untreated is far more dangerous. Your veterinarian can help you pick out the safest and most effective flea and tick treatment based on your dog’s age, lifestyle, health status and other unique characteristics.

By: Dr. Jennifer Coates, DVM

Featured Image: iStock.com/Gabi Uhrova