Chocolate toxicity in dogs

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Annandale Animal Hospital
62 Moore Street
Leichhardt
NSW 2040

Phone:
02 9550 9600
Fax:
02 9560 8503

Although chocolate is one of our favourite treats, many people are not aware of the fact that chocolate can be toxic (and sometimes even fatal) when shared with our canine friends. With Easter coming up, it is particularly important that all dog owners are aware of the risk of chocolate toxicity.

 

What makes chocolate toxic?

Chocolate, made from the beans of the cacao tree, contains a compound known as theobromine. Theobromine has a number of effects on the body. It stimulates both the cardiovascular and central nervous systems, raises blood pressure, has diuretic effects and in large enough doses can cause nausea and vomiting.

 

Why isn't chocolate toxic to humans?

Chocolate isn't toxic to humans as the human body has an increased ability to successfully breakdown and excrete theobromine. Dogs unfortunately do not have this luxury, and can get seriously ill if enough is ingested.

 

What are the signs of chocolate toxicity?

 

  • Signs most commonly occur within 12 hours of ingesting the chocolate, and include:
  • vomiting and diarrhoea
  • trembling and muscle spasms
  • increased excitement, irritability or nervousness
  • increased heart rate
  • excessive thirst and excessive urination (in higher doses)
  • seizures
  • coma
  • death (rare- usually due to cardiac disturbances)

 

How much chocolate do they need to eat for toxicity to occur?

The toxicity of theobromide is considered to be dose dependant. This means that a number of factors will influence if or to what degree an animal will be affected, including the type and amount of chocolate eaten, the size of the animal and the sensitivity of the individual

 

The concentration of theobromide differs between different types of chocolate.

 

  • milk chocolate contains approximately 1.5mg per gram
  • semi-sweet chocolate contains approximately 5.3mg per gram
  • unsweetened (baker's) chocolate contains approximately 13.9mg per gram
  • white chocolate does contain some theobromine but in such small amounts toxicity is unlikely

The toxic dose for theobromine is reported as 100-150mg per kg body weight, however occasionally problems are observed at doses as low as 20mg/kg. What this means in a practical sense, using 100mg/kg as a guide this equates to:

 

  • approximately 60 grams of milk chocolate per kg bodyweight
  • approximately 20 grams of semi-sweet chocolate per kg body weight
  • approximately 7 grams per kg body weight for baker's chocolate per kg body weight

From this you can see that the toxic dose is dependant on the weight of the dog, and that unsweetened cooking chocolate is particularly dangerous. Take an 8 kg miniature poodle for example. 100 grams of milk chocolate is unlikely to cause more than a digestive upset, whereas just over half that much unsweetened cooking chocolate could have devastating effects.

 

What should I do if I suspect my pet has eaten chocolate?

We recommend that dogs never be fed any form of chocolate. If you suspect that your dog has eaten a significant or unknown amount of chocolate you should always call a veterinary clinic for advice.

 

What treatment options are available?

As there is no antitoxin available for theobromine, the only treatment available is supportive therapy.

If an animal is presented less than four hours after ingestion, vomiting will be induced. When an animal is presented greater than four hours after ingestion or continues to show signs of toxicity after vomiting is induced, then activated charcoal is administered, which helps prevent further toxin absorption from the gut.

Intravenous therapy is always indicated to help flush the toxin out of the body faster, and is also essential to prevent and/or treat the severe dehydration that can occur as a consequence of the vomiting, diarrhoea and/or increased urination.

Complications of theobromine toxicity include seizures, muscle tremors and disturbances of heart rhythm. Anticonvulsant and antiarrhythmic drugs may be indicated in these cases.