There is a substance in chocolate called theobromine which poisons the dog and can cause vomiting, diarrhea and other abdominal issues. Dogs take longer to digest chocolate so you may not see symptoms right away. Overconsumption of theobromine can lead to epileptic fits, shock and possibly death.

With this in mind, however, it's important to note that different chocolates contain different levels of theobromine, with white chocolate being the least and dark chocolate (think Belgian chocolates) containing the most. If Fido picks up a Milky Way from the floor and munches on it - and happens to be a 100lb Labrador - you're probably OK. A smaller dog might get sick or even die depending on the concentration of theobromine in a small chocolate, but a larger dog may be all right.

For gardeners, reconstituted cocoa bean shells are available as mulch and while they smell great, if you have dogs or wandering neighbourhood dogs you may want to rethink your purchase of these items in the interest of general canine health.
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Types of Chocolate
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The different forms of chocolate and its by-products contain different amounts of theobromine.

The following list is in decreasing order of quantities of theobromine:


Cocoa Beans
Cocoa Powder
Plain (Dark) Chocolate
Milk Chocolate
Drinking Chocolate (Powder)
White Chocolate
For example, little Tiddlely-pom-pom, a 3 Kilo Pomeranian would need to gobble up a whole slab of chocolate, all at once, to be seriously affected. Furthermore, scientific studies on the subject do not seem to exist either … take my word for it, millions of healthy dogs, with fat butts, all over the world, enjoy the odd chocolate with no serious ill effects.