Chocolate is toxic to dogs because of a compound known as theobromine. Theobromine acts similar to caffeine. While it is relatively rare for chocolate toxicity to be fatal, it can cause very serious illness in many dogs.
The type of chocolate and how much is consumed is directly correlated to how ill dogs become. White chocolate poses the smallest risk since it has a very low concentration of theobromine at about 0.25 milligrams per ounce. Baking chocolate and high quality dark chocolate pose the greatest risk because they have the highest concentration of theobromine ranging from 100-400 milligrams per ounce. Milk chocolate is somewhere in the middle with about 45-55 milligrams of theobromine per ounce. This means a 50 pound dog would experience symptoms of chocolate toxicity from 8 ounces of milk chocolate or only one ounce of baking chocolate.
Symptoms of chocolate ingestion and their severity are linked to how much theobromine is ingested. It can take hours to see symptoms and in some cases they can last days. The most common symptoms are vomiting, diarrhea, elevated heart rate, panting, increased urination, restlessness and sometimes seizures. In dogs with preexisting heart conditions the symptoms and outcomes may be more serious. The reason symptoms can last so long is that theobromine has a long half-life in the body and can take a long time to be fully eliminated.
There are many ways to treat chocolate toxicity that vary widely based on what symptoms the patient is showing as well as where the pet is in the illness progression. Dogs that present right after ingesting chocolate typically have the best chance of avoiding symptoms if they are forced to vomit up the material. Dogs that are experiencing symptoms at the time of presentation will have to be treated based on their current needs. The best way to prevent these issues is to keep chocolate products in a safe place away from your pet's reach.
Photo Credit: Eric Rayner (CC)