Enter your dog's weight and what they ate — get an instant theobromine dose or risk tier, not just a vague warning.
It depends on your dog's weight and the type of chocolate. The Merck Veterinary Manual cites mild signs at around 20 mg/kg of theobromine, cardiac effects at 40–50 mg/kg, and seizures at 60 mg/kg or above — darker, less sweet chocolate is far more concentrated than milk chocolate, so a much smaller amount can reach these thresholds.
White chocolate contains only trace theobromine and is unlikely to cause chocolate poisoning, though its high fat and sugar content can still cause stomach upset or, in some dogs, pancreatitis.
There is no confirmed safe amount — some dogs have developed acute kidney injury after eating only a handful of grapes or raisins, while others tolerate larger amounts without apparent harm. Veterinary guidance is to treat any meaningful ingestion as a reason to contact your vet.
Yes. Chocolate symptoms can take up to 24 hours to appear, and grape/raisin kidney injury often develops 24–72 hours after ingestion — "seeming fine" in the first hours doesn't rule out a problem developing later.