The U.S. Food and Drug Administration is warning pet owners and veterinarians of the risk of serious neurologic events including seizures, muscle tremors, and ataxia in dogs and cats treated with certain flea and tick medications.
Pet owners using flea and tick medications in the isoxazoline class – specifically Bravecto (tablets for dogs OR topical for dogs or cats), Nexgard (tablets for dogs) or Simparica (tablets for dogs), Credelio (tablets for dogs) and Revolution Plus (topical solution for cats) – are urged to closely monitor their pets for adverse neurologic events.
Since these products obtained their respective FDA approvals, data received by the agency as part of its routine post-marketing activities indicates that some animals receiving Bravecto, Nexgard or Simparica have experienced adverse events such as muscle tremors, ataxia, and seizures. Another product in this class, Credelio, recently received FDA approval. These products are approved for the treatment and prevention of flea infestations, and the treatment and control of tick infestations.
The FDA is working with manufacturers of isoxazoline products to include new label information to highlight neurologic events because these events were seen consistently across the isoxazoline class of products.
The FDA carefully reviewed studies and other data on Bravecto, Credelio, Nexgard and Simparica prior to approval, and these products continue to be safe and effective for the majority of animals. The agency is asking the manufacturers to make the changes to the product labeling in order to provide veterinarians and pet owners with the information they need to make treatment decisions for each pet on an individual basis. Veterinarians should use their specialized training to review their patients’ medical histories and determine, in consultation with pet owners, whether a product in the isoxazoline class is appropriate for the pet.
The FDA continues to monitor adverse drug event reports for these products and encourages pet owners and veterinarians to report adverse drug events. You can do this by reporting to the drugs’ manufacturers, who are required to report this information to the FDA, or by submitting a report directly to the FDA.
To report suspected adverse drug events for these products and/or obtain a copy of the Safety Data Sheet (SDS) or for technical assistance, contact the appropriate manufacturers at the following phone numbers:
Merck Animal Health (Bravecto): 800-224-5318
Elanco Animal Health (Credelio): 888-545-5973
Merial (Nexgard): 888-637-4251
Zoetis (Simparica): 888-963-8471
Pet owners and veterinarians who have additional questions can contact AskCVM@fda.hhs.gov or call 240-402-7002.