SSRIs, SNRIs and tricyclic antidepressants can cause serotonin syndrome and seizures in dogs.
Includes Prozac, Zoloft, Lexapro, Cymbalta and Effexor.
Antidepressants increase serotonin (and sometimes norepinephrine) availability in the brain. In overdose this can cause serotonin syndrome — hyperthermia, tremors, agitation and cardiovascular instability. Tricyclics additionally cause severe cardiac arrhythmias by blocking sodium channels.
Sources
Toxicity can occur at doses just above the human therapeutic range. Even one missed/found pill in a small dog warrants vet advice.
Contact your veterinarian or an emergency animal poison hotline immediately. Do not induce vomiting unless instructed by a vet.
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