For milk chocolate, approximately 62 g/kg (1 oz/lb) is potentially lethal to dogs. A chocolate toxicity calculator can determine toxicity based on an animal's weight and the amount and type of chocolate ingested.
The outcome of chocolate toxicity depends on the amount and type ingested, the dogs weight and how promptly treatment was initiated. Delaying treatment from the time a dog eats chocolate can worsen the associated clinical signs and prognosis. Darker and more bitter chocolates are more toxic to dogs, but all forms of chocolate carry some risks.

Furthermore, visual representations like the one above help us fully grasp the concept of Signs Of Milk Chocolate Ingestion In Puppies.
Chocolate toxicosis in animals may result in potentially life-threatening cardiac arrhythmias and CNS dysfunction. Chocolate poisoning occurs most commonly in dogs, although many species are susceptible. Dogs are most often affected because of their indiscriminate eating habits and easy access to sources of chocolate.

Chocolate toxicity dogs peaks on holidays. Learn risky chocolate types, symptoms, and safe 3% hydrogen peroxide dosing for dogs (not cats).
Keep in mind, with any poisoning, its always cheaper, less invasive, and has a better prognosis/outcome if you treat early. If your dog has already developed clinical signs associated with chocolate toxicity, the veterinarian visit may be more expensive, and the outcome may be worse.