A Treat for Humans, a Danger for Dogs
Chocolate is one of the most popular treats in the world for people, but for dogs it can be genuinely dangerous. Many dog owners have heard the warning to keep chocolate away from their pets, yet not everyone knows the reason behind it. The danger is real and well understood by veterinarians, and it comes down to a specific substance found naturally in chocolate that the canine body simply cannot handle the way humans can.
The Culprit: Theobromine
Chocolate is made from the seeds of the cacao tree, and these seeds naturally contain a substance called theobromine, along with a smaller amount of caffeine. Theobromine is a stimulant, meaning it speeds up certain body functions such as heart rate. In humans, theobromine is generally harmless in normal amounts because the human body processes and removes it fairly quickly. The problem for dogs lies in how differently their bodies deal with this exact same substance.
Why Dogs Cannot Handle It
The core of the danger is that dogs break down, or metabolize, theobromine far more slowly than humans do. When a dog eats chocolate, the theobromine stays in its system much longer and can build up to levels that become toxic. This buildup can overstimulate the dog's heart and nervous system. Depending on how much was eaten, the effects can range from vomiting, restlessness, and a racing heart to, in severe cases, tremors, seizures, and serious heart problems.
Not All Chocolate Is Equal
The amount of theobromine in chocolate varies a great deal depending on the type, and this directly affects how dangerous it is. In general, the darker and more bitter the chocolate, the more theobromine it contains, which makes it more dangerous. Baking chocolate, cocoa powder, and dark chocolate carry the highest levels, while milk chocolate has much less, and white chocolate contains only tiny traces. Because the risk also depends on the dog's size and how much was eaten, the safest approach is simply to keep all chocolate well out of a dog's reach, and to contact a veterinarian quickly if a dog does eat some.
Source
This article was written using information from Wikipedia.