Chocolate Toxicity

How is chocolate toxic to dogs?

Chocolate contains compounds called methylxanthines including both theobromine and caffeine. These drugs cause stimulation of the central nervous system (brain and spinal cord), stimulation of the heart muscle and diuresis (increased urination), as well as a number of other effects.

What are the signs of chocolate toxicity?

Clinical signs are generally seen within 2-4 hours of ingestion of chocolate. Mild signs generally include restlessness, anxiety and hyper-excitability.

More severe clinical signs, which require veterinary attention include:

  • Vomiting and diarrhoea
  • Muscle tremors or muscle weakness
  • Seizures which can lead to unconsciousness

Other toxicities such as pesticides, nicotine and anti-depressants can also cause similar clinical signs. If you know your dog or cat ingested chocolate, you should seek veterinary advice immediately.

How much chocolate is poisonous to animals?

The lethal dose of chocolate is provided in the table below. This is enough chocolate to KILL the animal. Much less is required to make the animal unwell.

Grams of chocolate required to cause serious illness or death 

4kg cat 5kg dog 10kg dog 20kg dog 

Lethal dose of theobromine 320-600mg 500-1000mg 1000-2000mg 2000-4000mg 

How much cooking chocolate?  20-40g 35-70g 70-140g 140-280g 

How much dark chocolate? 60-120g 100-200g 200-400g 400-800g 

How much milk chocolate? 180-350g 280-560g 560-1120g 1120-2240g     

How is chocolate toxicity treated?

Like many toxicities, chocolate toxicity is treated with supportive care (fluid support, oxygen supplementation) and symptomatic treatment (e.g. the control of seizures). Fully conscious animal that have ingested the chocolate recently can sometimes be made to vomit or given activated charcoal which binds and removes the toxin. Treatments after this time depend on the amount of chocolate ingested and the clinical state of the patient.

Please call the team at Duncan McGinness Veterinary Surgery (02 6884 9900 or after hours 0418638380) if you have any questions regarding chocolate toxicity.

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