Question submitted during The Canine Epilepsy Summit:
"Thoughts about flea & tick preventatives causing seizures in dogs? The warnings state seizures are possible ... Is this one time or ongoing?
Also, does this usually occur Immediately or is there a delay? Does age of the dog matter?"
- Answer provided by Karen Muñana, DVM, MS, DACVIM (Neurology):
In 2021, the FDA issued a warning to alert pet owners about the potential for neurologic adverse events, including seizures, with flea and tick preventatives in the isoxazoline class. This class includes the following preventatives for dogs: Bravecto, Nexgard, Credelio, and Simparica (Trio). Because of this, the FDA recommends using these drugs with caution in dogs with a history of seizures. However, this does not mean that seizures will occur with use of these medications - most dogs tolerate these drugs with no issues.
If a dog with epilepsy is on one of these medications and is doing well, then I do not think any change is needed. If seizures are to occur with these preventatives, it will likely occur shortly after administration. So if a temporal pattern can be demonstrated between the seizures and the administration of the preventative, then it might be useful to try a different preventative that is in a different class of drugs.
Puppies are more susceptible to some adverse effects from preventatives, which is why the drugs are only approved for dogs over a certain age, but within that age range there should not be a difference in susceptibility to seizures. I do recommend using preventatives, particularly in areas where fleas and ticks are common, because disease associated with flea and tick infections can be significant. It is also important to keep dogs on heartworm preventative.
