Chocolate Toxicity – By: Dr. Cindy Krane

Chocolate is a delicious, decadent treat, and a gift from loved ones and chocolatiers world wide. It is also a natural renewable resource, and grows on trees. More precisely it grows on Cacao trees in South America, Africa, Indonesia and all along the equator. The Cacao tree, Theobroma Cacao, is a small tree in the understory of the rain forest sheltered by banana and coconut trees. The tree bears large, football shaped fruits called pods. Within each pod are hundreds of beans. During processing the seeds are roasted, ground and pressed. This separates the cocoa butter, which is the oily, fatty portion. The hulled seeds (cocoa beans) are further ground to make chocolate liquor. This is a misnomer as it does not contain any alcohol.

While Theobroma Cacao translates to “Food for the Gods” chocolate is not an appropriate food for dogs. In fact, it is one of the most dangerous foods for dogs and is amongst one of the most commonly reported household toxins. Christmas, Hanukah, Kwanza, New Years and Valentines Day are a very dangerous time of year for dogs with a sweet tooth.

Chocolate is a mixture of cocoa beans and cocoa butter. Chocolate contains toxic metabolites called methylxanthines namely theobromine and caffeine. These metabolites cause adverse effects on the gastrointestinal tract, neurologic and cardiovascular systems. Other sources of methylxanthines include cocoa mulch, No-doze tablets and other pharmaceutically prepared caffeinated products.

Chocolate is as appeasing to pets as it is to people. The aroma and palatability packed into attractive shine wrappers can be tempting for our furry friends. Urban, indoor, smaller and younger dogs are at the highest risks as they tend to get into the most trouble. Cats are rarely affected because; well because when it comes to food, cats more discriminating than dogs. Chocolate is dose dependent meaning the degree of toxicity is directly proportionate to the amount ingested as well as the size of the dog.

Toxicity is dependent on how dark and how much chocolate liquor the product has. From most to least toxic; dry cocoa powder dark, unsweetened baking chocolate, semi sweet chocolate, instant cocoa, milk chocolate, then white chocolate. In fact, white chocolate is not even chocolate at all – it contains no cocoa beans, just cocoa butter, sugar, butter fat, and other flavorings. As a general rule the less sweet, the more toxic.

For example, less than one ounce of milk chocolate (per pound of dog) is potentially lethal and less than 1/10 of an ounce of unsweetened baking chocolate (per pound) of dog is lethal.

Chocolate toxicity can affect 3 different organ systems. The first organ system is the intestinal tract and at higher doses the neurologic and cardiovascular systems are adversely affected.

Within 2-4 hours of ingestion, chocolate causes acute vomiting and diarrhea. Protracted vomiting and diarrhea occurs and is followed by excessive thirst. Occasionally, if consumed within a baked sweet or with other fatty foods, in addition to gastroenteritis pancreatitis can develop. This in itself can require hospitalization and can be life threatening.

If a toxic dose of chocolate is ingested, neurologic signs can develop. They typically start with early restlessness, excessive stimulation, enhanced alertness, hyperactivity, and progress to tremors and full blown seizure activity. High fevers can spike.

If a toxic dose of chocolate is ingested, cardiac signs can develop. Cardiac toxicity results from excessive contraction of the heart muscle and results tachyarrhythmia. This abnormal heart rhythm is so rapid that the heart does not have adequate time to fill with blood before each beat thus is unable to supply the body with properly oxygenated blood. As the cardiac toxicity progresses the heart rate and blood pressure drop to potential lethal levels within 12-36 hours.

While there is no antidote or specific treatment for chocolate toxicity, aggressive and early intervention is the key to a positive case outcome. The goal is to avoid further absorption of the toxins from the GI tract into the blood stream. Once the toxins reach the blood stream they travel to the central nervous system and cardiovascular systems. In attempts to limit these unwanted effects vomiting should be induced, the stomach contents lavaged (stomach pumped) and activated charcoal be administered. IV and urinary catheters should be placed to provide fluids for support and to keep the bladder empty. Supportive care and continuous monitoring of the heart rate, ECG, blood pressure, urine output and neurologic status. The seizures can be controlled with valium and other anti-seizure medications as needed. The cardiac arrhythmia may be treated with lidocaine, propanolol and other medications as needed. The duration of treatment can range form 12-36 hours; with best prognosis if treatment is initiated within 2-4 hours of ingestion. Prognosis is guarded to grave if the patient is already seizing or showing cardiac signs upon presentation to the veterinarians’ office.