Chocolate contains a compound chemical that is toxic dogs and cats called theobromine. It can affect the brain, heart, nerves and gastrointestinal tract.
The darker the chocolate (which means the higher the percentage of cocoa in the product), the more toxic it is to your animal. So for example white chocolate is the least toxic whereas cocoa powder and baking chocolate are significantly more toxic.
Symptoms might include excessive thirst/urination, hyperactivity, tremors, vomiting, diarrhoea, seizures, lack of coordination, and in severe cases death.
Within four hours of ingestion you should expect to see vomiting. An oral charcoal solution must be applied within the first four hours to prevent further absorption of the toxin.
With appropriate treatment the prognosis for an animal that has ingested chocolate is usually good and they can be discharged from your clinic within 24 hours. Remember to monitor your pet for several weeks after the event as the high fat content in some chocolates can be associated with a tummy upset.