Why a 100g bar hits a 15 kg dog hard
Theobromine toxicity depends on both the dog's size and the chocolate's cocoa content. Your 15 kg dog eating 100g of 70% dark chocolate has consumed roughly 700mg of theobromine—well into the danger zone for tremors, seizures, or heart issues. Dogs process theobromine slowly, so symptoms can take 6-12 hours to appear but escalate quickly once they start. At this dose, waiting to see symptoms isn't safe.
Dark chocolate packs 5-10 times more theobromine than milk chocolate, and 70% cocoa is at the higher end. The wrapper's weight and percentage are critical because vets calculate risk based on mg/kg. For perspective, a 30 kg dog might handle this amount with monitoring, but at half that weight, your dog needs proactive care.
What the vet will ask when you call
Have the chocolate wrapper in hand—the vet needs the exact weight (100g), cocoa percentage (70%), and brand if possible, as some contain extra caffeine. Time matters: 20 minutes ago means decontamination may still be an option at the clinic. They'll also ask if your dog has heart conditions or a history of seizures, which worsen the risk.
Expect questions about current behavior: pacing, panting, or restlessness are early red flags. Even if your dog seems fine now, emphasize the amount eaten and cocoa percentage—some clinics prioritize cases based on these numbers. If they advise coming in, go immediately; theobromine absorption can be delayed with high-fat foods like chocolate.
What to watch for in the next six hours
Early signs include vomiting (never induce it yourself), diarrhea, or excessive thirst. More severe cases progress to muscle tremors—often starting at the ears or face—then irregular heartbeat or collapse. Smaller dogs like yours may show symptoms sooner than larger breeds due to the higher mg/kg ratio.
Keep your dog in a quiet, dimly lit room; stimulation can worsen tremors or seizures. Note any changes in gum color (pale or blue-tinged means emergency) or breathing rate. Even if symptoms seem mild at first, they can escalate rapidly around the 4-hour mark as the liver metabolizes the theobromine.
How to prevent repeat incidents
Store chocolate in closed cabinets above counter height—dogs can smell it through packaging and will chew through bags or boxes. Teach a "leave it" command using high-value treats as positive reinforcement. For households with kids, use clear containers so spills are visible, and never leave chocolate in backpacks or low drawers.
Consider keeping carob treats (theobromine-free) on hand for times when family eats chocolate around the dog. If your dog is a repeat counter-surfer, baby-proof latches on cabinets or a designated "no pets" snack zone can help. After this scare, it's worth pet-proofing more thoroughly—dogs remember where they found high-value items like chocolate.
For a dose worked out against your pet's weight, use the Chocolate Toxicity Calculator.