Chocolate contains the chemical methylxanthine theobromine, which is toxic to dogs. The severity and timing of initial symptoms depends on the amount and type of chocolate a dog ingests. While chocolate poisoning is seldom fatal, immediate treatment after ingestion reduces the severity of toxicity.
Symptoms of chocolate poisoning typically begin within two to four hours after ingestion. They include vomiting and diarrhea. These symptoms are followed by hyperactivity, muscle tremors, rapid pulse, increased urination and fever. In severe cases, symptoms such as seizures, coma, heart failure and death can occur within 12 to 36 hours of ingestion. If you suspect your dog ate chocolate, contact your veterinarian immediately. Induced vomiting and activated charcoal treatments can help remove much of the theobromine if administered within the first two hours after ingestion.