Why Is Chocolate Poisonous For Dogs And Not People?

WARNING: If you think that your dog has eaten chocolate, please call your vet and seek advice immediately. Treatment for chocolate poisoning in dogs is usually successful but this depends on how much chocolate has been eaten and how quickly veterinary treatment is started – so please call your vet now.


Chocolate contains chocolate toxicity in dogsa substance called theobromine, which is similar to caffeine. In large amounts, theobromine can be toxic for both dogs and humans; however toxicity is very rare in people even when very large quantities of chocolate are consumed.

Dogs metabolise, or break down, theobromine much more slowly than humans. This is why a relatively small amount of chocolate can be very bad for your dog. Chocolate is also toxic for other pet species including cats, but most problems are seen in dogs as many of them love the taste of chocolate and will eat as much as they can get their paws on!

Chocolate types

Different types of chocolate have varying amounts of theobromine in them; generally, the more cocoa solids contained in a product, the more theobromine will be present and the more dangerous the item is for your dog. The amount of theobromine in different chocolate types is shown below in milligrammes (mg) of theobromine per gramme of chocolate:-

  • Cooking or baking chocolate (dark) – 16mg per gramme
  • Dark chocolate – 5.5mg per gramme
  • Milk chocolate – 2.4mg per gramme
  • White chocolate – 0.01mg per gramme

The amount of theobromine that is fatal for dogs is given as between 100 and 250 mg per kg of the dog’s bodyweight. So if your dog weights only 10kg, as little as 60-70g of cooking chocolate could be fatal. This is not very much chocolate!  With milk chocolate, the same dog would need to eat around 500g. White chocolate contains very little theobromine, and toxicity is unlikely, but if your dog eats a lot of it there may still be signs of gastrointestinal upset.

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An increase in cases of chocolate poisoning often occurs around Christmas and Easter, as there is more chocolate in the house and opportunistic dogs find ways of getting to it!

Signs your dog may show

Signs of chocolate toxicity are usually seen within 2 to 4 hours of your dog eating the chocolate. The signs that you see will depend on the quantity of theobromine that has been eaten.

Lower Doses

Signs include vomiting and diarrhoea, which can be severe.

Higher Doses

Vomiting and diarrhoea as above.

Nervous system signs including restlessness, panting, muscle stiffness, uncoordinated movement, seizures (‘fits’), and in very severe cases, loss of consciousness.

The heart can also be affected at higher doses; heart rate increases and your dog may also suffer from irregular heart rhythm.

All of these symptoms can cause serious problems for your dog, and require assessment and treatment by your vet.

If you suspect your dog has eaten chocolate, call your vet immediately. They will ask you questions as to how much and what type of chocolate your dog has eaten and is likely to want to see your pet immediately for assessment and supportive treatment.

What your vet may do

When you take your dog in to the surgery, the treatment he receives will depend on the amount of chocolate eaten and the symptoms being shown. Initial treatment involves removing the chocolate from your dog and decreasing absorption of the toxins in your pet’s intestinal tract. So your vet may:-

  • Cause your dog to vomit to remove the remaining chocolate
  • Give your dog activated charcoal to decrease further absorption in the gut
  • Put your pet on a drip to maintain circulating blood volume and encourage excretion of toxins in the urine.
  • If neurological signs such as seizures are present these will be treated as a matter of urgency
  • Where your dog’s heart shows a dangerously fast rate or rhythm abnormality, these will also be addressed with medication.


Symptoms generally last for between 12 and 30 hours following ingestion of chocolate. Overall the outlook for your pet should be good as long as he receives appropriate treatment from your vet as soon as possible after the chocolate is consumed.

Other foods that are toxic for dogs include:

There are online chocolate toxicity calculators that may help you as a guide but they are not a substitute for getting veterinary advice.