Any time a pet ingests a toxin that you are not sure about, I recommend calling the ASPCA poison control:  https://www.aspca.org/pet-care/animal-poison-control

They are open 24 hours a day and can help you calculate the dose that was ingested if there is anything to worry about and how severe the symptoms may be.   As always with drugs, it always depends on the dosage that was received.  Anything can be toxic in the right dose.  However, there was a study with this medication tested on dogs here in which the dogs weighing less than 11.4 kg were given 5mg tablets with the most severe symptom being vomiting. https://europepmc.org/articles/pmc339203