Chocolate may be America’s favorite flavor. We like chocolate candy, ice cream, chocolate drinks, chocolate cakes, and just about anything with chocolate. We may want to share our favorite treat with an eager pet but it is best to think twice and reach for the dog biscuits instead.

Different Types of Chocolate and How They Are Made

Anyone who has ever eaten candy knows there are many types of chocolate: milk, dark, white, unsweetened, cocoa powder, etc. It turns out each type has a different potential for toxicity. In order to understand which types of chocolates are more toxic, we will need to review how chocolate is made.

Cocao trees, which require a tropical climate, are farmed in orchards like any other fruit-bearing tree. The fruit of the cacao tree, called a cacao pod, is sweet and attracts monkeys or other wildlife who eat the fruit but not the bitter seeds. The seeds are discarded in the natural setting, allowing new trees to grow. Outside of the farm situation, the seeds cannot be released from the fruit unless some type of animal breaks the fruit open. Ironically, it is the bitter seeds, packed with theobromine and caffeine, which are used to make chocolate.

The pods grow directly off the trunk of the cacao tree and must be harvested by hand so as not to damage the tree. The pods are split, and the seeds are scooped out and left to ferment under banana leaves for about a week. This process turns the cocoa seeds into the rich brown color with which we are familiar and creates the chocolate flavor we crave.

The seeds are then dried out for another week, packed in sacks, and shipped to chocolate manufacturers. The seeds must be roasted, ground, pressed to remove the seed oil (this oil is called cocoa butter, which is used in sunscreens, white chocolate, and cosmetics, among other things), and finally tempered to create the exact consistency.

• Chocolate liquor is the liquid that results from grinding the hulled cacao beans.
• Cocoa butter is the fat that is extracted from chocolate liquor. It is combined with sugar and flavoring to create white chocolate. White chocolate is not directly toxic as it has no chocolate liquor, but its rich fat content can be a problem, as discussed below.
• Cocoa powder is the solid that remains after the cocoa butter is removed from the chocolate liquor. The powder can be treated with alkali in a process called Dutching, or it can be left alone. Note the low-fat nature of cocoa powder, hence its use in low-fat baking.
• Unsweetened (baking) chocolate is basically straight chocolate liquor containing 50% to 60% cocoa butter.
• Dark chocolate (also known as semisweet chocolate) is chocolate that is 35% chocolate liquor (the rest being sugar, vanilla, or lecithin).
• Milk chocolate is chocolate that is at least 10% chocolate liquor, the rest being milk solids, vanilla, or lecithin.
• Chocolate liquor is the one with all the problem biochemicals. The more chocolate liquor is in the end product (i.e., how dark the chocolate is), the more toxic it is.                                                                                                                                                                                                                                                       

Pancreatitis

Sometimes we eat chocolate plain, as in candy. Sometimes we eat it baked into cakes, mixed into ice cream, etc. Sometimes we share these treats with pets, and sometimes, our pets share these treats without our permission. As far as pets are concerned, the first potential problem with these sweets is the fat. A sudden high-fat meal (such as demolishing a bag of chocolate bars left accessible at Halloween time) can create a lethal metabolic disease in dogs called pancreatitis.  Vomiting, diarrhea, and abdominal pain are just the beginning of this disaster. Remember, in the case of pancreatitis, it is the fat that causes the problem more than the chocolate itself.

The fat and sugar in the chocolate can create an unpleasant but temporary upset stomach. This is what happens in most chocolate ingestion cases.

Theobromine and Caffeine

Chocolate is, however, directly toxic because it contains methylxanthines. In particular, the methylxanthines chocolate contains are theobromine and caffeine. Both caffeine and theobromine produce similar effects, with the theobromine effects lasting much longer than the caffeine. The more chocolate liquor there is in a product, the more theobromine there is. This makes baking chocolate the worst for pets, followed by semisweet and dark chocolate, followed by milk chocolate, followed by chocolate-flavored cakes or cookies.

Theobromine causes:

• Vomiting 
• Diarrhea 
• Hyperactivity 
• Tremors 
• Seizures 
• Racing heart rhythm progressing to abnormal rhythms 
• Death in severe cases

Toxic doses of theobromine are 9 mg per pound of the dog’s weight for mild signs and up to 18 mg per pound for severe signs. Milk chocolate contains 44 mg per ounce of theobromine, semisweet chocolate contains 150 mg per ounce, and baking chocolate contains 390 mg per ounce. White chocolate has virtually no theobromine and is only a problem because of its fat content. These calculations seem complex, and they certainly can be. What it boils down to is that your veterinarian will need to know the type of chocolate and how many ounces were most likely consumed. If it is not clear how much chocolate was actually consumed, the largest possible amount should be determined based on how much candy, cake, etc., is missing.

It takes nearly four days for the effects of chocolate to work its way out of a dog’s system. If the chocolate was only just eaten, it is possible to induce vomiting; otherwise, hospitalization and support are needed. It is common for clinics to receive phone calls about pets who were found to have consumed a chocolate product, and the owner wishes to know if the amount was toxic. In order to answer such questions, it is necessary to know the pet's weight, the type of chocolate, and the amount of chocolate. Chocolate calculators are available at most veterinary practices, and it can be determined relatively quickly if the pet should be made to vomit immediately. 

Treatment

As mentioned, the first step is to remove as much chocolate from the body as possible by inducing vomiting or using adsorbents such as activated charcoal to bind the chocolate and keep it from being absorbed by the GI tract.  For many patients, removing undigested chocolate converts the toxicity from neurologic poisoning to just an upset stomach that is easily managed. If too much caffeine/theobromine has been absorbed, the treatment is support: sedation for the tremors and intravenous medications for any cardiac arrhythmias. Support is needed until the toxins have been processed and removed from the body so expect severe cases to need intravenous fluid support and hospitalization for a few days.

Related Links

Pet Poison Hotline