Various chocolate

Vet Lessons

Various chocolateMany of you found discussing a real veterinary clinical case interesting last month and so here’s a seasonal problem that we get faced with pretty much every year during the festive period: chocolate toxicity. Some of you may already be aware of the fact that chocolate is actually toxic to dogs, but for lots of people, clients included, this is something that they have no idea about.

Dogs being dogs will generally eat anything and everything, and with lots of advent calendars and selection boxes around in December, it is more likely that they will eat chocolate and get into trouble. So, get your teeth around this case and help reduce the number of dogs we see on Christmas Day šŸ™‚

This month’s festive topic is….

Chocolate Toxicity

Virtually every Christmas, and Easter for that matter, we get phone calls from worried owners who report that their dogs have managed to devour a load of chocolate, either as a result of being typical dogs and seeking out food, or by inadvertantly being fed the stuff by a well meaning individual, normally a child who thinks its fun to share their chocolate with the family dog. It is not a great surprise to learn that the vast majority of these cases I have seen are Labrador Retrievers, such is their almost manic love of food.

Now we all know that chocolate can be bad for our waistlines but the thought of one of our favourite treats actually being toxic seems like a completely alien concept. The reason chocolate is of concern in dogs is due to a substance called theobromine, which is a natural component of chocolate, with dark chocolate containing more than milk and white chocolate. Theobromine is actually toxic to humans, if consumed in large enough quantities, but it is the fact that dogs metabolise it much slower than humans which makes it significantly more likely that we see signs of toxicity in them.

The clinical signs associated with chocolate toxicity generally include nausea, vomiting, diarrhoea, collapse, seizure, abnormal heart rate and rhythm, and increased urination. When we get calls from owners who say their dog has eaten chocolate the main questions we ask, before advising them to head straight down to the clinic, include:

  1. How much, in terms of total weight, of the chocolate do they believe their dog ate? This helps us to determine whether the amount of chocolate, and thus theobromine, is considered to be at toxic levels.
  2. What type of chocolate was it and what is the percentage of cocoa contained (eg 70%). Darker chocolate contains more cocoa, and thus theobromine, than milk chocolate. Knowing the percentage of cocoa and the amount of chocolate eaten allows us to accurately determine whether toxic levels have been consumed. This relies on us also knowing the dog’s bodyweight, which we double check when they come in to see the vet.

Some of the dogs we see who have eaten chocolate will be bright as buttons, whilst others will come in collapsed and showing obvious clinical signs of poisoning. These dogs are usually the ones who have either eaten chocolate several hours before, and so had time to absorb the theobromine and develop signs associated with it, or who have eaten very large quantities recently. I normally perform a clinical exam on the patient, take a fuller history from the owner, confirm the answers to the questions above and ask to see the packet of the chocolate, assuming the owner has brought it with them, which you should really ask them to do. I then weigh the dog and give the Veterinary Poisons Information Service (VPIS) a call, as they are a fantastic source of advice and guidance on currently known toxic doses of various substances and advice on ideal management and treatment.

If the dog has eaten chocolate less than 2 hours before we see them then we make them sick, usually by giving an injection of apomorphine, which is a powerful emetic (makes animals vomit). This often works within five minutes of giving it and the result is usually a nice, sticky, sweet-smelling pile of vomit for all to enjoy – lovely part of the job!

If it has been over 2 hours since ingestion then it is often too late to make them vomit, as most of the chocolate will have been digested and the theobromine absorbed. Whether our patients are made to throw up or not, we usually take a blood sample to check the dog’s kidney parameters, as the kidneys can be affected by theobromine. We then start the dog on a drip, to keep the dog well hydrated and help flush the kidneys through. If the dog will eat, which many will, then we start feeding them bland food with activated charcoal in it every few hours. The charcoal acts to bind and absorb any chocolate still in the dog’s intestines and prevent it being absorbed into the blood. We continue with this measure until we see the dog passing black charcoal in it’s faeces. Sometimes the toxic effects of theobromine can take up to 72 hours, or 3 days, to show and so we usually keep the dog on fluids for at least 24 hours, but often longer, and recheck the kidney values regularly, in case we see any evidence of late kidney effects. As a result, the cost of treating a case of chocolate toxicity can be very high, something that pet owners may have trouble appreciating and understanding, especially when what they can see is an apparently fit and healthy dog.

If there are any other, more serious signs associated with chocolate toxicity, such as seizuring, then we deal with those. These measures may well include:

  • Vomiting & Diarrhoea – we give gastro-protectants (medicines which help reduce acid production in the stomach and protect the lining of the intestines), anti-emetics (medicines to prevent the dog feeling nauseous and throwing up). We may also offer kaolin-based gels, which help to reduce diarrhoea and make the stools firmer.
  • Cardiac (heart) arrhythmias – we monitor the dog’s heart rate and rhythm with an ECG and give medication to correct any abnormal rhythms if they occur.
  • Seizures – giving anti-seizure medication, such as barbiturates (eg diazepam) is the method for dealing with seizures.

Assuming that the patient responds well to treatment, and we catch the case early enough, then they often make a full recovery and can be sent home. It is vital that the owners are well educated about the dangers of chocolate in dogs in order to significantly reduce the chances of toxicity happening again.

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