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What Makes Chocolate Toxic, And What Are The Signs Seen With Toxicity?

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Chocolate Demise by foooooey on Flickr

Chocolate Demise

by foooooey on Flickr
Question: What Makes Chocolate Toxic, And What Are The Signs Seen With Toxicity?

All About Chocolate Toxicity > What makes chocolate toxic

Chocolate is a popular treat all year round. Care must be taken when animals are around, though. Chocolate can be toxic, and sometimes even fatal, for animals. Dogs are most commonly affected, due to their ability to find it and the common 'sweet tooth' they seem to have. It is important to remember that cats and other species are susceptible to the toxic effects of chocolate, too.

Answer: Chocolate is made from the fruit (beans) of the cacao tree. Theobromine, a component of chocolate, is the toxic compound in chocolate. (Caffeine is also present in chocolate, but in much smaller amounts than Theobromine.)

Unsweetened (baker's) chocolate contains 8-10 times the amount of Theobromine as milk chocolate. Semi-sweet chocolate falls roughly in between the two for Theobromine content. White chocolate contains Theobromine, but in such small amounts that Theobromine poisoning is unlikely.

From The Merck Veterinary Manual, here are approximate Theobromine levels of different types of chocolate:

  • Dry cocoa powder = 800 mg/oz
  • Unsweetened (Baker's) chocolate = 450 mg/oz
  • Cocoa bean mulch = 255 mg/oz
  • semisweet chocolate and sweet dark chocolate is = 150-160 mg/oz
  • Milk chocolate = 44-64 mg Theobromine per oz chocolate
  • White chocolate contains an insignificant source of methylxanthines.
Source: Merck Veterinary Manual Online

The toxic dose of Theobromine (and caffeine) for pets is 100-200mg/kg. (1 kiliogram = 2.2 pounds). However, according to the poison control center at the ASPCA, problems have been noted at doses much lower than this - i.e. 20mg/kg. Translated to a "typical" scenario, and using the 20mg/kg as a measure of "problems can be seen at this level of ingestion", a 50 pound dog would have to consume 9 ounces (+/-) of milk chocolate to consume the 20mg/kg amount of Theobromine.

Some dogs won't see problems at this rate. Some may. This is a much more conservative toxic level calculation than the "standard" of 100-200mg/kg, but better safe than sorry.

Signs are most commonly seen within 12 hours (or less) of chocolate ingestion.

  • Excitement / nervousness / trembling
  • Vomiting / diarrhea
  • Excessive thirst / sometimes excessive urination (at higher levels of Theobromine toxicity)
  • Muscle spasms
  • Seizures
  • Coma (rare
  • Death (rare) -- likely due to heart rhythm abnormalities.

The Big Question: Why isn't chocolate toxic to humans?
Humans can break down and excrete Theobromine much more efficiently than dogs.

If you suspect that your pet has ingested chocolate, please contact your veterinarian for advice and treatment.

All About Chocolate Toxicity > What makes chocolate toxic

Photo: Chocolate Demise by foooooey on Flickr

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