What makes chocolate so dangerous for dogs?

Chocolate — it’s hard to find someone who doesn’t like it. But this is one of the most toxic foods your dog can eat. Nearly every pet owner has a horror story about their dog hoovering a chocolate bunny at Easter, or getting into a chocolate cake during a birthday party. Dogs move fast when they see something they want to eat and during holidays or events, it can be hard to keep track of your dog.

But chocolate is renowned for being bad for dogs and for good reason. 

Chocolate contains theobromine.

“They key to chocolate’s deadliness is a bitter-tasting chemical called theobromine,” writes Ross Pomeroy in an article in Forbes. Pomeroy writes that theobromine is an alkaloid present naturally in cacao beans, which are the building block of the commercial chocolate we all love. But the amounts present in chocolate products are small enough that people have nothing to worry about. Pomeroy’s article does the math for us: an average ten year old child would need to eat about 1,900 Hershey’s milk chocolate miniature candies to get chocolate poisoning. 

Dogs, however, can’t process theobromine the same way humans do and it stays in their systems longer.

“[Dogs] metabolize theobromine about five times more slowly, so the compound has much more time to accumulate in their bodies to toxic levels,” Pomeroy, a zoologist and conservation biologists, explains.

Every type of chocolate contains different amounts of theobromine. Dark chocolate is more dangerous, while milk chocolate contains lower amounts of theobromine per ounce. According to an article by vet Ahna Brutlag the Associate Director of Veterinary Services at VCA Hospitals, many dogs can consume small amounts of milk chocolate without any harm. The article, ‘Chocolate Poisoning in Dogs,’ states that white chocolate “barely poses any threat of chocolate poisoning.” 

The most toxic forms of chocolate, according to the American Kennel Club are:

  • cocoa powder

  • unsweetened bakers chocolate

  • semisweet chocolate

  • dark chocolate

  • milk chocolate

“Theobromine primarily affects the central nervous system, cardiovascular system, and respiratory system, as well as having a diuretic effect,” writes Fiona Finlay in an article on chocolate poisoning on the US National Library of Medicine National Institutes of Health website. She notes that a lethal dose is between 100 to 500 milligrams per kilogram of body weight in dogs. 

But because every type of chocolate or chocolate based goodie contains varying amounts of theobromine, it’s hard for dog owners to calculate a “safe” amount of chocolate for their dog. 

Better safe than sorry. Never feed your dog chocolate as a treat. If your dog, depending on its size, gets its mouth on a chocolate chip or a crumb of cake, it’s likely she or he will be fine. 

If your dog does get into a chocolate treat, your first move is to call your vet or animal hospital. 

Before calling, attempt to determine:

  • How much chocolate your dog consumed
  • What kind of chocolate your dog ate 
  • How much your dog weighs

Vets may be able to assess over the phone if you need to bring your dog in right away, or just keep an eye on it for symptoms of chocolate poisoning. Larger dogs can consume more chocolate than a small dog. There are online calculators to determine the danger to your dog, but a quick call to a trusted vet is always recommended. 

Clinical signs of chocolate poisoning typically manifest within six to 12 hours after your dog eats chocolate. 

A small amount of chocolate may result in diarrhea or vomiting, but large amounts cause more serious symptoms like muscle tremors, seizures, an irregular heartbeat, internal breathing or a heart attack. If your dog is acting hyperactive and this isn’t normal, let your vet know this when you call. Increased thirst, panting, and excessive urination are also symptoms of poisoning.