Concerns grow over oral flea and tick medications for dogs amid neurological risks
When dog owners give their furry companions medications to ward off fleas and ticks, they expect protection—not the risk of tremors, seizures, or loss of coordination. Yet recent studies and warnings from the U.S. Food and Drug Administration (FDA) have highlighted potential neurological side effects linked to popular oral treatments like Bravecto, NexGard, Simparica, and Credelio. This has sparked debate among veterinarians and pet owners: Are the benefits of these medications worth the risks?
In Sonoma County and beyond, veterinarians are carefully weighing these concerns as the threat of dangerous tick-borne diseases continues to grow.
The FDA’s 2018 warning highlighted adverse events related to isoxazoline medications. Reports submitted to the agency included seizures, lethargy, and loss of coordination in dogs, even in those with no prior history of neurological conditions. The FDA recommended that pet owners consult their veterinarians before starting any isoxazoline treatment. Full details of the warning can be found in the FDA’s fact sheet on isoxazoline products.
A 2021 study published in Frontiers in Veterinary Science analyzed thousands of adverse event reports and found a low but measurable risk of neurological side effects in dogs treated with isoxazoline drugs. The researchers noted that although most dogs tolerate these drugs well, those with pre-existing neurological issues may be more vulnerable. You can read the full study in Frontiers in Veterinary Science.
Some veterinarians are seeing an increase in seizure cases potentially linked to oral flea preventatives, but many still consider these medications essential for combating flea and tick infestations, particularly in areas with high disease risk.
An article from Veterinary Practice News highlights the divide in veterinary opinion. Some vets argue that the risk of adverse reactions is outweighed by the benefit of preventing diseases like Lyme disease, which has been on the rise in many parts of California.
Dr. Todd Archer, a board-certified veterinary neurologist, said in a separate interview with DVM360, “If there are dogs with a history of neurological conditions or if clients are concerned, alternatives like topical preventatives should be discussed.”
The FDA continues to track reports of adverse effects through its Adverse Event Reporting System. Pet owners are encouraged to report any side effects that occur after their pets take medications like Bravecto, NexGard, Simparica, or Credelio. Reports from the system help the FDA assess whether further safety measures are needed.
Despite these reports, serious reactions remain relatively rare compared to the millions of doses administered each year. Many veterinarians emphasize that cases of severe side effects are isolated and can often be managed through early detection and intervention.
For pet owners who prefer to avoid oral medications, there are other options such as topical treatments and flea collars. Products like the Seresto collar are widely used, though even these have faced scrutiny. A 2021 USA Today investigation reported that the Seresto collar was linked to a number of adverse reactions, prompting calls for further safety reviews.
Other options include non-chemical strategies like regular grooming, the use of flea combs, and natural repellents. However, these methods are generally less effective for controlling severe infestations. Veterinarians typically recommend using a combination of approaches during peak flea and tick seasons.
Experts recommend that pet owners take a few key steps when choosing flea and tick prevention for their dogs:
1. Consult your veterinarian: Discuss your dog’s medical history, especially if neurological conditions are present.
2. Monitor for warning signs: Look for signs of adverse reactions, such as tremors, seizures, or difficulty walking, and report them promptly.
3. Report side effects: Submit any adverse reactions to both your veterinarian and the FDA’s reporting system.
4. Consider alternatives: Explore topical treatments, collars, or non-chemical approaches if your dog is at high risk for neurological side effects.
More information about the FDA’s guidance on isoxazoline products is available on their official website.
