Why Can't Dogs Eat Chocolate?

Everyone has heard about the myth that feeding chocolate to your pooch will lead to devastating side effects, maybe even death. Has anyone ever seen a dog die from eating an M&M? Probably not, so what's the big deal about feeding the dog a few pieces of chocolate every now and then?

The chocolate that we eat comes from the bitter seeds of the cacao tree, which contain a family of compounds called methylxanthines. In humans methylxanthines lead to bronchial smooth muscle relaxation which helps to dilate constricted airways, stimulates diuresis to help relieve congestion, and acts as a mild cardiac and central nervous system stimulant. These compounds, however, contain two substances that are detrimental to dogs: caffeine and theobromine.

Caffeine and theobromine bind to receptors on the surfaces of dog's cells and act as competitive inhibitors by blocking the ligands that normally bind there. The results are frightening in canines: muscle tremors, seizures, vomiting, diarrhea, and a doubled increase in heart rate. The type of chocolate also matters - unsweetened baking chocolate has a much higher ratio of theobromine than does milk chocolate. Even a few ounces of milk chocolate can mean death for a small dog. Other foods/drinks that contain methylxanthines include coffee, cocoa, cola nut (used in cola drinks), and black teas.

Although most dogs do survive the typical bout with chocolate "poisoning," vets and researchers recommend avoiding the substance for your furry friend altogether.