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.