One of the most common phone calls we get as veterinarians is about dogs ingesting chocolate. In fact, when a veterinarian is “on call” during Easter, Halloween, or Christmas, he or she can pretty much plan on it!
Chocolate contains theobromine, which is a methylxanthine similar to caffeine. Dark chocolate is the most toxic, especially unsweetened baking chocolate and cocoa powder. Clinical signs associated with chocolate toxicity include vomiting, excitement, tremors and seizures. It also causes the heart to speed up and become irregular. If enough chocolate is ingested, it can lead to death. If you see your dog ingest chocolate, do not wait until you see these signs. Call your veterinarian immediately, so that they may induce vomiting if necessary.
To avoid chocolate toxicity, make sure to keep all chocolate candies and baking chocolate up high in the pantry, where the dog has no chance of reaching it. Be especially wary of Christmas gifts that may contain chocolate (or coffee for that matter) and do not place such gifts under the Christmas tree. There is also a type of mulch, made from cacao bean hulls that should be avoided if one has a dog.
Here is a list that shows the relative amount of theobromine in different types of chocolate:
Unsweetened Baking Chocolate- 390-450 mg/oz
Cacao Powder- 400-737 mg/oz
Dark Semisweet Chocolate- 135 mg/oz
Milk Chocolate- 44-60 mg/oz
White Chocolate- 0.25 mg/oz
Cacao Bean Mulch- 56-900 mg/oz
A rule of thumb is that a 20 pound dog can be poisoned by eating 2.25 oz of baking chocolate or 20 oz of milk chocolate. If you see your dog eat any amount of chocolate, however, call your veterinarian.