Chocolate, much like coffee and other food products, contains a stimulant chemical known as theobromine that has a marked effect upon the body and physical functions of animals. While unlike caffeine theobromine does not provide a major “rush” of energy it does work to increase the bodily functions and stimulate various systems in a number of ways. The two animals that have the largest effect from this, in fact, are both dogs and horses.

Given theobromine’s status as a stimulant it was once used to improve the performance of race horses in a more “natural” way, though since its original usage in this regard it has since been banned. While this was once done with little or no impact to the health of a horse due to its size and ability to process the theobromine dogs do not have this luxury, and as such even moderate amounts may prove deadly.

While consuming a small amount of chocolate may not be deadly to a dog even moderate amounts can prove deadly in the right situation. The additional stimulation provided by theobromine may cause the dog to die from multiple system failure or simply cardiac arrest, put the animal into a coma due to the chemical overload occurring in its brain or even give it seizures from the blood flow irregularities theobromine induces.

While a dog’s body will true to purge itself of theobromine in a number of ways should it consume too much it may not always be able to do this. Some common ways that this is done is through vomiting, diarrhea, increased urination, increased panting, crying (to release the theobromine through tear ducts) and even muscle twitching to allow any of the chemical that might remain present in muscular tissue to be metabolized and cleared out of the system.

Other common symptoms of theobromine poisoning include an elevated heart rate and other increased functions, much like humans have when consuming too much coffee. In short, while it may not be as poisonous as some other chemicals to the animal (such as cyanide) it is still a potentially deadly toxin that should be avoided at all times if possible.