Chocolate Toxicosis

Chocolate toxicosis refers to poisoning by chocolate. The substance that causes the poisoning is theobromine, which is found in chocolate, cocoa, tea, and colas. Dogs are more susceptible to chocolate poisoning because of their appetite for sweets. Poisoning in cats has not been reported, probably because they do not care for sweets as much as dogs do.

Milk chocolate contains about 44 mg of theobromine per ounce of chocolate, and unsweetened or baking chocolate has about 390 mg per ounce (1 ounce=28,000 mg). The actual poisonous dose of theobromine differs among dogs and depends on the individual dog's own system, but half of all dogs will experience poisoning if they consume 125 to 250mg of theobromine for each pound of body weight. For example, if a 1-pound dog eats 3 ounces of milk chocolate, it would have a 50% chance of being poisoned. A 10-pound dog would have to eat 30 ounces or a little less than 2 pounds of milk chocolate to have a 50% chance of being poisoned. Poisoning has occurred with smaller amounts of ingested theobromine, but most poisonous doses fall within the range given above.

Chocolate poisons dogs by causing the release of powerful body stimulants, such as epinephrine and norepinephrine. It also alters calcium use by muscles.

Signs of chocolate poisoning include vomiting, diarrhea, increased urination, changes in heart rate and rhythm, staggering, muscle twitching, coma, and possible death.