My 12-year-old Yorkie ate a double dose of Simparica Trio. Is he safe?
Hello, thank you for using PetCoach.
Please understand that we are not an emergency service. If you are worried your pet have ingested something toxic you need to call your local veterinary emergency clinic or ASPCA Animal Poison Control as we cannot guarantee a prompt response. Some toxicities are true emergencies and can be fatal.
( https://www.aspca.org/pet-care/animal-poison-control )
Typically speaking most (not all) animals that ingest a double dose of a preventive medication are safe however, not all animals react to medications the same way. The best you can do if it has been more than an hour since he ingested it is to watch for symptoms of toxicity like: tremors, seizures, ataxia (walking drunk/unsteady), extreme lethargy, vomiting, etc.
If you notice any symptoms get him to an emergency clinic ASAP.
As an aside, according to studies done by Zoetis who make Simparica, "In the overdose groups, transient and self-limiting neurological signs were observed in some animals: mild tremors at 3 times the maximum exposure dose and convulsions at 5 times the maximum exposure dose. All dogs recovered without treatment." Again, this won't hold true for every individual.
Hope this helps. Best wishes.
Updated on September 23rd, 2025