Chocolate toxicosis results from ingestion of excessive amounts of methylxanthine-containing chocolate products. Clinical effects include vomiting, restlessness, agitation, hyperthermia, tachycardia, and, in severe cases, seizures.
This phenomenon, known as chocolate poisoning in dogs, can range in severity from mild digestive upset to life-threatening complications. Early signs often include vomiting, diarrhea, and restlessness, while advanced cases may result in rapid heart rate, seizures, and, in rare instances, death.

Two toxic components to dogs found in chocolate are caffeine and theobromine, which predominately cause stimulation of the central nervous system and heart. They also act as diuretics, which can quickly lead to dehydration.

Learn what makes chocolate toxic to dogs, what symptoms to expect by timeline, and exactly what to do if your dog ate chocolate including when it's a true emergency.
The effects of chocolate consumption in dogs depend on how much chocolate was ingested and the size (body weight) of the dog. Dogs are at risk of clinical signs from consuming more than 0.5 ounces of milk chocolate per pound of body weight.