Theobromine poisoning

Animal	Oral toxicity (mg/kg)
	TDLo	LD50
Cat		200
Dog	16	300
Human	26	~1000
Mouse		837
Rat		1265

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

In general, the amount of theobromine found in chocolate is small enough such that chocolate can be safely consumed by humans. However occasional serious side effects may result from the consumption of large quantities, especially in the elderly.^[1] In extreme cases, emergency room treatment may be required.^[2]

Serious poisoning happens more frequently in domestic animals, which metabolize theobromine much more slowly than humans, and can easily consume enough chocolate to cause chocolate poisoning. The most common victims of theobromine poisoning are dogs,^[3][4][5] for which it can be fatal. The toxic dose for cats is even lower than for dogs. However, cats are less prone to eating chocolate since they are unable to taste sweetness.^[6] Theobromine is much less toxic to rats and mice, due to their relative genetic similarity to primates; they and humans all have an LD50 about 1000 mg/kg.

Toxic (LD50) doses of theobromine have only been published for humans, cats, dogs, rats, and mice; these differ by a factor of 6 across species (see the table in this article). The toxicity for (pet) birds is not known, but it is typically assumed that chocolate is dangerous for birds, especially since birds like to eat chocolate.^[7]

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.

In dogs, the half-life of theobromine is 17.5 hours, so in severe cases clinical symptoms of theobromine poisoning can persist for 72 hours.^[8] Medical treatment performed by a veterinarian involves inducing vomiting within two hours of ingestion and administration of benzodiazepines or barbiturates for seizures, antiarrhythmics for heart arrhythmias, and fluid diuresis.

A typical 20 kg (44 lb) dog will normally experience intestinal distress after eating less than 240 g (8.5 oz) of dark chocolate, but won't necessarily experience bradycardia or tachyarrhythmia unless it eats at least half a kilogram (1.1 lb) 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.^{[citation needed]} For example, a typical 25-gram (1-ounce) baker's chocolate bar would be enough to bring out symptoms in a 20-kilogram (44-pound) dog. Large breeds (>100 lbs) can safely consume chocolate in limited quantities, but care must still be taken, as they can safely eat only about a quarter the amount a human can, and should not be intentionally fed it; peanut butter is often recommended as a safer alternative.

Chemists with the USDA are investigating the use of theobromine as a toxicant to control coyotes that prey on livestock.^[9]

Footnotes

1. ^ THEOBROMINE from the Hazardous Substances Data Bank
2. ^ emergency treatment of theobromine poisoning, from the Hazardous Substances Data Bank^{[broken citation]}
3. ^ "Dog owners get chocolate warning". BBC. December 30, 2008. http://news.bbc.co.uk/1/hi/england/derbyshire/7805430.stm. Retrieved July 28, 2009. 
4. ^ "Chocolate Poisoning in the Dog". Vetrica. February 9, 2004. http://www.vetrica.com/care/dog/chocolate.shtml. Retrieved July 28, 2009. 
5. ^ "Greedy dog cheats chocolate death". BBC. April 3, 2009. http://news.bbc.co.uk/1/hi/england/hampshire/7982311.stm. Retrieved July 28, 2009. 
6. ^ Biello, David (August 16, 2007). "Strange but True: Cats Cannot Taste Sweets". Scientific American. http://www.scientificamerican.com/article.cfm?id=strange-but-true-cats-cannot-taste-sweets. Retrieved July 28, 2009. 
7. ^ B. Harvey, Toxicoses in Birds. (unknown date and original publisher)
8. ^ Gwaltney-Brant, Sharon (February, 2001). "Chocolate Intoxication". Veterinary Medicine Publishing Group. http://www.aspcapro.org/mydocuments/m-toxbrief_0201.pdf. Retrieved November 05, 2011. 
9. ^ Johnston, John J. (2005). "Evaluation of Cocoa- and Coffee-Derived Methylxanthines as Toxicants for the Control of Pest Coyotes". Journal of Agricultural and Food Chemistry. http://digitalcommons.unl.edu/cgi/viewcontent.cgi?article=1014&context=icwdm_usdanwrc. Retrieved July 28, 2009. 

References

• Theobromine in the ChemIDplus database (September 9, 2004)
• Merck Veterinary Manual (Toxicology/Food Hazards section), Merck & Co., Inc., Chocolate Poisoning. (June 16, 2005)
• [1]

External links

• Chocolate Toxicity Calculator
• A Pet Owner's Guide to Poisons: Chocolate
• Toxicity basic facts
• The science behind the toxicity