Chocolate contains two ingredients that dogs’ bodies can’t process: caffeine and theobromine. In fact, these ingredients are toxic when a dog ingests them and can cause serious illness and even death, says Timothy Hackett, D.V.M., associate professor of emergency and critical care medicine at Colorado State University. If you’re worried your pooch has broken into your Halloween stash, watch for the following symptoms: vomiting, diarrhea, increased urination, restlessness, hyperactivity, a “drunken” walk or body tremors. If you notice any of these signs, rush your dog to a vet immediately. Your veterinarian will induce vomiting and monitor your dog’s heart. If Fido seems fine after a forbidden chocolate feast, try to figure out how much chocolate he ate and what type (dark chocolate can cause more damage thanks to its higher concentration of theobromine), and call your vet to see if the amount ingested was a toxic dose.