Halloween is coming soon, and remember how much dogs love to tear open those bags of M&M's. Chocolate is toxic to dogs, and high doses can be lethal. The active ingredient is theobromine, and depending on the amount and type of chocolate consumed, clinical signs ranging from mild stomach upset, to severe vomiting and diarrhea, thirst, panting, tremors and seizures, can be seen. If ingestion is witnessed, call you friends at Westgate Pet Clinic. Based on the information you give them, they will calculate whether the ingested dose was toxic to your pet. Vomiting is promptly induced, and other treatments are often necessary, but as usual, prevention is the best cure.