Why Are Dogs Allergic to Chocolate?



dogs and chocolate

We’ve all heard that we’re not supposed to give our dogs chocolate. But why exactly is that? Why is chocolate so bad for them?

The Deadly Ingredient

It turns out that chocolate contains a chemical called “theobromine,” which is an alkaloid similar to those found in caffeine. Theobromine is a central nervous system stimulant that raises blood pressure, heart rate, and brain electrical activity. Dogs, cats, and horses can’t process theobromine like humans can, meaning that foods such as chocolate and caffeine can cause severe effects and even fatalities.


Symptoms of theobromine overdose in dogs include whining, diarrhea, vomiting, seizures, muscle twitching, dehydration, and rapid heart rate- the last of which can cause death. Hyperactive behavior, excessive panting, increased urination, and digestive problems can also occur.

The levels of theobromine poisoning vary due to the dog’s size, age, and the amount or type of chocolate consumed. Older dogs have a harder time processing theobromine, and are more likely to experience potentially fatal symptoms such as rapid heart rate. The larger the dog, the more they can process. Smaller dogs have a lower threshold for theobromine poisoning.

Some Chocolates Are More Toxic Than Others

The type of chocolate also matters. Cocoa powder contains high amounts of theobromine- almost sixteen times as much as milk chocolate. For milk chocolate, the toxicity level is one ounce per pound of body weight; a twenty-pound dog would die without medical intervention after eating twenty ounces of milk chocolate. For dark chocolate, the ratio is one-third of an ounce per pound of body weight, and for baker’s chocolate it’s one-ninth. However, white chocolate contains very little theobromine and is not generally toxic to animals. PetMD has a cool and nifty Chocolate Toxicity Meter. The meter factors in your dog’s weight, the type of chocolate and amount of chocolate consumed and then provides you with a description of the potential symptoms your dog may experience.

Dogs and chocolate

What Should I Do If My Dog Ate Chocolate?

If you suspect your dog has eaten chocolate, contact your veterinarian immediately. You can also call the ASPCA Animal Poison Control hotline at 888-426-4435. They are available for emergencies 24 hours a day, every day of the year (a consultant fee may apply).  In most cases, the vet will induce vomiting immediately.

Theobromine’s half-life is 17.5 hours, so if you get your pet prompt medical attention and your pet is doing well at the 24-hour mark, he or she has a good chance of making it out of the woods.

Other Foods To Avoid

Chocolate isn’t the only food that’s bad for dogs. Grapes, raisins, onions, macadamia nuts, and yeast are all toxic as well. So is hops, a common ingredient in beer. Sugar-free candies with xylitol can cause liver damage, so it’s another food that shouldn’t be shared with your furry friend. Other potential hazards around the house are antifreeze, alcohols, rat poison, and pain medications such as Tylenol. If you suspect your dog has consumed any of the above, call the vet immediately to discuss a treatment plan and see if you need to bring your little guy or gal into the clinic.

Important Note:
This advice is not a substitute for a proper veterinarian consultation and is only intended as a guide. Please contact your local veterinary practice for advice or treatment immediately if you are worried about your pet’s health.

Photo Credit:  istockphoto.com


Gerald Owens, has a vision – to create an online community that embraces all aspects to having and caring for pets. Our mission is to provide pet “guardians” with accurate, relevant information on how to have happier and healthier animal companions.