Have you ever wondered why it is that chocolate is dangerous for dogs, and yet kids can consume and adults indulge with no ill effect (well, aside from a sugar high and excess of calories)?
It all comes down to species differences in metabolism. Each species has evolved to eat certain foods. They have their own system of digesting, absorbing, processing, and excreting the waste products of their food. There is a lot of overlap in metabolic processes between species, but the differences are key to understanding why chocolate is a treat for some and toxic for others.
What is toxic in chocolate?
Chocolate is made from cocoa beans (plus sugar and milk and various other ingredients to make it sweet and tasty). Cocoa beans contain several compounds which interact with our body systems- including beneficial antioxidants and flavanols. Importantly, chocolate also contains caffeine and theobromine. You can think of theobromine as caffeine’s (slightly more chilled) cousin as they have similar effects on the body. Theobromine, because it is present in chocolate in greater amounts, is the main cause of chocolate toxicity.
The dose makes the poison …
At lower doses, caffeine and theobromine can be beneficial- they act as stimulants by improving alertness and influencing our mood (as anyone who relies on their morning coffee can attest). At higher doses (like when someone has had one too many expressos or caffeinated energy drinks) you begin to see other effects including changes to heart rate and rhythm, diuresis (increased urine production), restlessness, and even gastrointestinal upsets (vomiting or diarrhoea). These are the signs seen in mild chocolate toxicity. The higher the dose of caffeine/ theobromine, the worse the adverse effects- dogs with severe chocolate toxicity can develop muscle tremors, seizures, and can even die from heart failure.
The difference between dogs and people
Human metabolism is much more efficient at digesting and excreting caffeine and theobromine than dog metabolism. The half-life (the time taken for half of what we have ingested to be eliminated) for caffeine is 3-5 hours in humans versus 7 hours in dogs. For theobromine the difference in half-life is 7-10 hours in people versus 18-hours in dogs. This means that caffeine and theobromine build-up in a dog’s body, increasing their effective ‘dose’ and therefore their risk of experiencing toxic side effects.
What about cats?
Cats, like dogs, are slow to metabolise caffeine and theobromine. However, they rarely suffer from chocolate toxicity. Why? Because cats lack sweet taste receptors … and therefore chocolate does not hold much appeal for them. Dogs on the other hand, have very similar taste receptors to humans and can detect and enjoy the sweet flavours that make chocolate so delicious.
Not all chocolates are equal
The amount of caffeine and theobromine in chocolate depends on the type of chocolate … or more specifically, on the percentage of cocoa in the chocolate. Cocoa powder and baking chocolate present the highest risk, followed by dark chocolate and semisweet chocolate, then milk chocolate. White chocolate does not actually contain any cocoa solids and therefore has no caffeine or theobromine to worry about.
What to do if your pet has eaten chocolate?
Call your vet! Try to make a note of how much your pet has (possibly) eaten and what sort of chocolate it was. Your vet will then be able to advise if the dose has the potential to be toxic. There is no specific antidote to chocolate toxicity, only symptomatic therapy. But if dogs are seen soon enough, they can be induced to vomit the chocolate back up, which normally prevents clinical signs developing.
The number one solution for chocolate toxicity however, is to guard your chocolates! Keep them safely away from your pet because prevention is always better than treatment. Particularly if it means you get more chocolate to enjoy yourself!!
Disclaimer: The information and advice in this post is general in nature. It is not intended as a substitute for tailored health care advice from your regular veterinarian.