Chocolate contains caffeine, which can give your dog stomach and intestinal (gastrointestinal) problems, as well as another dangerous compound called theobromine. The combination of caffeine and theobromine can affect your dog's gastrointestinal system, nervous system and heart if he consumes a large amount of chocolate at one time.

Poisoning can occur at a dose as low as 100 milligrams per kilogram of body weight. For a 16-pound dog, that means 1 pound of milk chocolate or just 4 ounces of baking chocolate. At doses of 200 milligrams per pound of body weight, chocolate can be lethal, so small dogs are particularly at risk.

Baking chocolate contains 450 milligrams of theobromine per ounce, semi-sweet chocolate contains 260 milligrams per ounce and milk chocolate contains 60 milligrams per ounce.

At lower doses, the symptoms of chocolate poisoning are primarily gastrointestinal. At high doses, your dog can die from irregular heartbeats (cardiac arrhythmia) or failure of the heart to beat (cardiac arrest).

Easter, Halloween and the December holiday season are times of particular danger. To be safe, always keep your eating and baking chocolate well out of your dog's reach.

Symptoms

• Vomiting
• Diarrhea
• Tremors or shaking
• Seizures or convulsions
• Frequent urination
• Lack of coordination or wobbly movements (ataxia)
• Elevated body temperature (hyperthermia)
• Irregular heartbeats (cardiac arrhythmia)

Diagnosis

The most important factors are the symptoms listed above and a history of exposure to chocolate. Blood tests generally do not show abnormalities when your dog has chocolate poisoning.

Therapy

The first priority is to remove any undigested chocolate by inducing vomiting and by pumping (lavaging) your dog's stomach. Also, the veterinarian may administer activated charcoal, which binds to caffeine and theobromine and thus prevents further absorption.

Theobromine has no antidote. Your dog will receive intravenous fluids and possibly oxygen. The veterinarian will treat abnormal heart rhythms and seizures as they occur.

Prognosis

With hospitalization and aggressive supportive care (for at least 12-48 hours), your dog is likely to recover. Occasionally a fatality occurs if a dog has consumed a large amount of chocolate (usually baking chocolate), and treatment has been delayed until the chocolate has been fully absorbed.