Why Are Dogs Allergic to Chocolate?

Dogs are not “allergic” to chocolate. Chocolate reacts differently to a dog’s body chemistry than to a human’s, so chocolate is actually poisonous to dogs. There is no need to panic if your dog sneaks a cookie crumb off the floor, however. The toxicity of chocolate in dogs varies by the type and amount of chocolate, and your dog’s weight is a factor in how much he will be affected by chocolate consumption.

Chocolate contains theobromine, which acts as a stimulant. In humans, the effect is similar to that of caffeine, but a dog’s body does not metabolize theobromine quickly. This prolongs and intensifies the effects of the stimulant, affecting the heart and nervous system. In sufficient amounts, this causes seizures and cardiac arrest.

Different types of chocolate contain varying levels of theobromine. Milk chocolate contains the least amount of theobromine per ounce--around 50 milligrams--while baking chocolate and cocoa powder contain the most at around 500 milligrams per ounce. According to the Talk to the Vet website, there has been at least one known case of a dog fatality due to cocoa bean mulch consumption.

A six-pound Yorkshire Terrier experiences seizures and possible death after consuming about four ounces of milk chocolate. This is the equivalent of around two and a half candy bars. However, less than one ounce of baking chocolate or half an ounce of cocoa powder could cause death in the same dog.

A 75-pound Golden Retriever could consume about 34 ounces of milk chocolate or five ounces of baking chocolate before experiencing seizures or potential death.

In smaller doses, the theobromine in chocolate makes dogs very sick and leads to potential kidney damage. The best rule of thumb is to keep all types of chocolate away from all types of dogs.

A dog suffering from theobromine overdose may exhibit several symptoms. First, he may appear hyper, showing excessive excitement or irritability. He may experience excessive urination and a racing heart. Symptoms may progress to vomiting, diarrhea, lethargy and muscle tremors. The next stage of symptoms may include seizures and death.

If your dog has consumed any dark chocolate, baking chocolate, cocoa powder or a significant amount of milk chocolate, contact an emergency hotline immediately. The ASPCA has an Animal Poison Control hotline with advice available for a fee charged to your credit card. You can also contact your veterinary clinic’s emergency hotline if available.

If it has been less than two hours since your dog ate the chocolate, you may be advised to induce vomiting. After two hours, the metabolic process has gone too far for vomiting to be beneficial. At this point, your dog must have professional medical care.