August 18, 2023 | General
According to this survey, two-thirds of 1,594 dogs given this common treatment experienced an adverse event, such as muscle tremors, reduced muscle control, seizures or death. Is your dog or cat taking any of these nine products that are FDA approved and prescribed by veterinarians?
In 2018, the U.S. Food and Drug Administration (FDA) issued an alert to pet owners and veterinarians about the potential for neurologic adverse events in dogs and cats treated with flea and tick products containing isoxazoline, a parasiticide (chemical insecticide). In 2019, the alert was updated to include two additional products, and it was updated again in 2021.
The quite serious side effects pets have experienced after being given products containing isoxazoline include muscle tremors, ataxia (loss of muscle control), and seizures. The implicated products have received FDA approval and include:
While the FDA “considers products in the isoxazoline class to be safe and effective for dogs and cats,” the agency asserts it is “providing this information so that pet owners and veterinarians can take it into consideration when choosing flea and tick products for their pets,” according to its fact sheet. Further, per the FDA:
I’m guessing most veterinarians who routinely prescribe chemical flea/tick products would only consider pets with a previous history of neurologic issues to be at risk. After all, there’s no way to predict a potential problem in healthy animals, and yet the FDA warns that, “… seizures may occur in animals without a prior history.”
While the FDA doesn’t provide specifics in its alert about adverse events, “Project Jake,” a pet owner and veterinarian online survey about flea and tick medications containing isoxazoline was wrapping up at around the same time the alert was issued in 2018. The survey findings involved 2,751 respondents and were released in June 2020.
According to veterinarian Dr. Jean Dodds, one of the co-authors of the study, the Project Jake survey was broadly based and included:
It’s also important to note that the survey ended before the FDA alert was released, so the results represent an objective review.
Of the 2,751 Project Jake survey responses (all involving dogs), 42% (1,157) reported no flea treatment or adverse events, 58% (1,594) reported that a pet had been treated with a flea control parasiticide, and of those, 83% (1,325) received a product containing isoxazoline. Of the 1,594 dogs given any flea treatment, 66.6% (1,062) had an adverse event (AE).
The Project Jake survey findings were compared to findings of the FDA and the European Medicines Agency (EMA). The number of total adverse events reported to the FDA and EMA were comparable, but there was a 7 to 10 times higher incidence of seizures and deaths reported by the EMA or from outside the U.S.
Serious adverse events involving neurological effects, seizures and deaths in the Project Jake findings were higher than the FDA but somewhat lower than the EMA reports. In addition, the number of reported deaths and seizures associated with flea treatments containing lotilaner and spinosad in the Project Jake results were considerably higher than product labelling suggests with regard to potential neurological effects.
The Project Jake study co-authors also raise concerns about human exposure to isoxazoline, as well as exposure through the food chain. From the study:
“Based on the results from the Project Jake survey and reviews of publicly available FDA and EMA AE reports demonstrating that cross-species neurotoxicity exists, the following issues also require further attention: Recognition of human exposure risk as delineated in package inserts, and concerns that may arise from recent proposals to repurpose isoxazoline veterinary drugs for application to vector-borne human diseases by treating humans (Miglianico et al., 2018).
Furthermore, there is a very real potential for food-chain associated AE, since fluralaner (as Exzolt) has recently been approved for treatment in poultry in Europe (Exzolt fluralaner for chickens).”
The position of the Project Jake study co-authors is that as a class of drugs, isoxazolines “can work as intrinsic neurotoxins across species.” In addition:
“The data also suggested notable differences in reporting of AE for the US versus European territories. This may reflect cultural tendencies and/or procedural methodologies for reporting of AE. Nevertheless, the national and international post-market safety survey data summarized here indicate an immediate need for continued cross-species studies and a critical review of product labelling by regulatory agencies and manufacturers.
Moreover, this class of drugs had more serious AE than those reported in the package inserts. We believe that the FDA should consider additional changes to their criteria for AE observation, and define what would be needed for future clearances of this class of drugs.”
You can find the full Project Jake survey results here.
While it’s true that some pets are given chemical flea/tick preventives regularly for a lifetime and have no observable adverse reactions, the volume of reports of negative outcomes connected to these products should have every pet parent asking, “Is it worth the risk?” In the majority of cases, my answer is no, and my advice is to exhaust all possible nontoxic alternatives first. Some I recommend include:
Neem oil is not an essential oil. It’s an expelled or pressed oil, and it’s safe for cats (I have a pest deterrent recipe for kitties I’ll give you in a second). Neem oil is effective because fleas and ticks hate it. It’s also great for animals who are very sensitive to smells.
Catnip oil can also be used as a pest deterrent, since it has been proven to be as effective as diethyltoluamide (DEET), the mosquito and tick spray humans use that has a number of toxic side effects.
If you want to add some extra punch to your dog’s pest recipe, go with an extra five drops of lemon, lemongrass, eucalyptus, or geranium oil. I use geranium oil quite a bit because I find it very effective. In fact, I use it in my Dr. Mercola natural flea and tick products. If you have a dog who comes in contact with ticks, adding the extra punch of one of the essential oils I listed can be very beneficial.
You can store your homemade pest deterrent in the fridge, which is what I do. Before my dogs head out in the morning, I mist them with it, being careful to avoid their eyes. The active ingredients, especially the oils in the recipe, dissipate in about four hours, so you may need to reapply it several times throughout the day.
Neither neem nor catnip oil are truly essential oils – they’re distillates, so we’re safe using those. Catnip oil works to deter mosquitoes as well. Cats aren’t prone to heartworm, which is a mosquito-borne disease, but dogs are.
So those are two easy, all-natural recipes you can use to deter pests and as a bonus, they also make your dog or cat smell wonderful! You can use them during flea season, tick season, and all summer long and feel good that you’re not using pesticides on your pet.
If you live in areas where pests are such a problem you have to use chemicals, consider starting with the Spinosad class of chemicals, which are derived from soil bacteria, and whenever you use chemicals, make sure to detox your pet simultaneously.