Dogs and Chocolate: Get the Facts

Most of us have heard that chocolate can make dogs sick. But how serious is the risk?

By Salynn Boyles
WebMD Pet Health Feature

Reviewed by Katherine Snyder, DVM

If your canine companion is more family member than pet, you may be in the habit of sharing the foods your family loves with him.

Although some people foods are fine in moderation, this is definitely not the case with chocolate.

Chocolate can sicken and even kill dogs, and it is one of the most common causes of canine poisoning, say veterinarians who spoke to WebMD.

Veterinarian Michelle DeHaven says the worst case of chocolate poisoning she ever saw happened when some owners fed their eight-pound poodle a pound of chocolate on his birthday.

“We had to treat the dog with fluids and anti-seizure medication for five days," says DeHaven, who practices in Smyrna, Ga. "Every time we stopped the meds he would start seizuring again. You wouldn't feed a kid a pound of chocolate, but they fed it to a small dog.”

Most experts say that although no amount of chocolate is OK for your dog to consume, it would take a large quantity to kill him. Furthermore, the real risk lies with dark and baker's chocolate; milk and white chocolate pose a much less serious risk.

What Makes Chocolate Poisonous to Dogs?

Chocolate is made from cocoa, and cocoa beans contain both caffeine and a related chemical compound called theobromine, which is the real danger.

The problem is that dogs metabolize theobromine much more slowly than humans, Denver veterinarian Kevin Fitzgerald, PhD, tells WebMD.

“The buzz we get from eating chocolate may last 20 to 40 minutes, but for dogs it lasts many hours,” he says. “After 17 hours, half of the theobromine a dog has ingested is still in the system.”

Theobromine is also toxic to cats, but there are very few reported cases of theobromine poisoning in felines because they rarely eat chocolate.

Dogs, on the other hand, will eat just about anything.

Even small amounts of chocolate can cause vomiting and diarrhea in dogs. Truly toxic amounts can induce hyperactivity, tremors, high blood pressure, a rapid heart rate, seizures, respiratory failure, and cardiac arrest.

Dogs and Chocolate: How Much is Too Much?

The more theobromine a cocoa product contains, the more poisonous it is to your dog.

Unsweetened bakers chocolate contains about 390 milligrams of theobromine per ounce -- about 10 times more than milk chocolate and more than twice as much as semi-sweet chocolate. White chocolate contains very little theobromine.

According to the Merck Veterinary Manual, once ounce of milk chocolate per pound of body weight is potentially lethal.

But the real danger lies with dark chocolate. Merck warns that deaths have been reported with theobromine doses as low as 115 milligrams per kilogram (2.2 pounds) of body weight.

So 20 ounces of milk chocolate, 10 ounces of semi-sweet chocolate, and just 2.25 ounces of baking chocolate could potentially kill a 22-pound dog, Fitzgerald says.

Serious toxic reactions can occur with ingestion of about 100 to 150 milligrams of theobromine per kilogram of body weight.

That means:

  • A 9-pound dog could be expected to exhibit symptoms of chocolate toxicity after eating 1 ounce of baking chocolate, 3 ounces of semi-sweet chocolate, or 9 ounces of milk chocolate.
  • A 27-pound dog might have such symptoms after eating 3 ounces of baking chocolate, 9 ounces of semi-sweet chocolate, and 27 ounces of milk chocolate.
  • A 63-pound dog might exhibit symptoms after eating 7 ounces of baking chocolate, 21 ounces of semi-sweet chocolate, or 63 ounces of milk chocolate.

“In 27 years of practice, I've seen two dogs die from eating chocolate,” says Fitzgerald, who appears regularly on Animal Planet's hit show Emergency Vets. “Both were under 20 pounds, both were elderly and both ate baking chocolate in very large amounts.”

Although most people would not eat a 4-ounce bar of bitter-tasting baking chocolate, this is not true of dogs, he says.

“Dogs experience the world through tasting it, and they are gorgers,” he says. “Baking chocolate tastes good to them.”