Toxic dose of theobromine for cats: >200 mg/kg
If your cat ate chocolate, contact your vet or pet poison helpline immediately.
Cats are more sensitive to theobromine than dogs. The toxic dose is approximately 200 mg/kg (lethal dose), but symptoms begin at 20 mg/kg. Theobromine content varies: white chocolate 0.9 mg/g, milk chocolate 1.5 mg/g, dark chocolate 5.3 mg/g, baking chocolate 14 mg/g, cocoa powder 28 mg/g. Symptoms appear 6-12 hours after ingestion: vomiting, diarrhea, hyperactivity, tremors, seizures, and cardiac arrhythmia. Cats rarely eat chocolate voluntarily (they lack sweet taste receptors), but it can happen with chocolate-flavored foods. Treatment: induce vomiting (if within 2 hours), activated charcoal, IV fluids, and supportive care. There is no antidote — treatment is supportive.