Chocolate itself is not dangerous, but the reaction of some of its chemical compounds with the metabolism of animals can cause real damage. The higher the cocoa content in the chocolate, the more dangerous its toxicity.
For a 40 kg dog, it will need to ingest 200 grams of 50% dark chocolate for the ingestion to be toxic. The symptoms of chocolate poisoning appear just a few hours after ingesting chocolate. The first symptoms are digestive. The animal will tend to vomit and have diarrhea. If the quantity ingested is large, it is possible that digestive disorders may be accompanied by neurological disorders.