Theobromine poisoning

Animal Oral toxicity (mg/kg)

Cat 200
Dog 300
Mouse 837
Rat 1265

Dog 16

Theobromine poisoning or chocolate poisoning is an adverse reaction to the alkaloid theobromine, found in chocolate, tea, cola beverages, and some other foods. Cacao beans contain about 1.2% theobromine by weight, while processed chocolate generally has smaller amounts. The amount found in highly refined chocolate candies (typically 40-60 milligrams per ounce or 1.4 to 2.1 grams per kilogram) is much lower than that of dark chocolate or unsweetened baker's chocolate (over 400 mg/oz or 14 g/kg).

The amount of theobromine found in chocolate is small enough that chocolate can be safely consumed by humans in large quantities, but animals that metabolize theobromine more slowly can easily consume enough chocolate to cause chocolate poisoning. The most common victims of theobromine poisoning are dogs (for which it can be fatal). Cats and especially kittens are yet more sensitive, and many other animals are also susceptible.

The first signs of theobromine poisoning are nausea, vomiting, diarrhea, and increased urination. These can progress to cardiac arrhythmias, epileptic seizures, internal bleeding, heart attacks, and eventually death.

Theobromine is especially toxic to horses, dogs, parrots, voles, and cats because they are unable to metabolize the chemical effectively. If they are fed chocolate, the theobromine will remain in their bloodstream for up to 20 hours. Medical treatment involves inducing vomiting within two hours of ingestion, or contacting a veterinarian.

A typical 20 kg dog will normally experience intestinal distress after eating less than 240 g of dark chocolate, but won't necessarily experience bradycardia or tachyarrhythmia unless it eats at least a half a kilogram of milk chocolate. According to the Merck Veterinary Manual, approximately 1.3 g of baker's chocolate per kilogram of a dog's body weight (0.02 oz/lb) is sufficient to cause symptoms of toxicity. For example, a typical 25 gram baker's chocolate bar would be enough to bring out symptoms in a 20 kg dog.

Theobromine @
Chocolate's Caffeine Cousin

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* Home > Theobromine (Molecule of the Month for February 2001)

Picture of Theobromine

click on the picture above to interact
with the 3D model of the
Theobromine structure

C7 H8 N4 O2

Beans from the Cacao Tree, Theobroma Cacao, are the source of the world's chocolate. The Principal Alkaloid of the Cacao Bean is theobromine, a close structural relative of caffeine. Theobromine differs from Caffeine by only one Methyl group.

Cacao contains between 1.5-3% Theobromine and 0.2-0.4% Caffeine. Theobromine is a minor constituent of tea but it is not present in coffee. Theobromine has a ten fold less stimulating effect to humans than caffine does. For dogs however, 100-200 mg of theobromine per kg of a dogs body weight can cause Cardiac and Central Nervous System distress. The average value of theobromine in Milk Chocolate: 200mg per 100g, Unsweetened Baking Chocolate: 1400mg per 100g, Cacao: 2600mg per 100g

The Aztec emperor Montezuma used to drink a goblet of chocolate before entering his harem each night, leading to the popular legend about Chocolate's Aphrodisiac Properties. But this legend may just have some truth to it... Chocolate contains three substances, caffeine, theobromine and phenyethylamine that might be related to this myth. Caffeine acts as a stimulant. Theobromine stimulates the heart muscle and the nervous system. Phenyethylamine is reputed (no conclusive proof exists yet) to be a mood elevator and an anti-depressant. The combination of these three substances, giving you extra energy, making your heart beat faster, making you a bit jumpy and slightly giddy....well, you can see how chocolate could be linked to love. But before you go out to buy several cases of chocolate to ply your lover with tonight, remember that these substances show up only in small quantities in chocolate.

Update by Karl Harrison

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