Here at the practice, we’re bracing ourselves for a run of poisoning cases at the end of this month… While chocolate is lovely for us, it’s lethal to our pets, but sadly, most dogs don’t realise this and are very keen to gobble up any Easter eggs or other sweet treats they can find!
What is the toxic ingredient?
Chocolate contains both theobromine and caffeine; these are part of the methylxanthine family. They are both toxic to many animals (and note that caffeine, for example, in coffee grounds, is just as dangerous) and affect the cardiovascular and nervous systems.
What animals are at risk?
Humans can metabolise (break down) these chemicals safely, but dogs, cats, and many other species are all potentially at risk. However, the majority of clinical cases we see are in dogs. Cats do not generally like sweet foods, and so are not so likely to eat large quantities. Dogs, however, often really love sweet things and are often greedy! As a result, it’s far more likely for a dog to eat a toxic quantity.
How does chocolate affect animals?
These toxins are rapidly absorbed through the gut, and then shut down certain processes within cells, as well as disrupting nerve signals in the brain.
The symptoms don’t usually appear until 6-12 hours after eating the chocolate. Initially, it looks like a stomach upset - vomiting, diarrhoea and excessive thirst. This then progresses to restlessness and hyperactivity.
If sufficient toxin has been eaten, abnormal heartbeats follow, along with difficulty breathing. Blueness of the gums and collapse may result, and the dog may suffer from seizures or go into a coma. If not treated, the affected animal may die of brain damage, heart failure or suffocation. In addition, many chocolate products contain so much fat that pancreatitis may be triggered.
How do I know if my pet is in danger?
Different types of chocolate contain different amounts of theobromine and caffeine. As a general rule of thumb, white chocolate is the least dangerous, milk chocolate is somewhere in between, and dark chocolate is the most dangerous. It’s important to remember it’s not just confectionery - cocoa powder is even more toxic than dark chocolate.
There aren’t any hard and fast rules for how much methylxanthine there is in a particular piece of chocolate, because it depends on the brand, the purity of the cocoa solids, and the amount of methylxanthine in the plants that the cocoa beans came from. However, as a general rule, milk chocolate contains about 2-3 milligrams per gram of chocolate (mg/g), sweet dark chocolate about 5-6mg/g, and premium dark (65% cocoa solids) roughly 10-11mg/g.
For most dogs (cats are thought to be more sensitive, but there’s less data available), toxic effects start at about 20mg/kg bodyweight, heart problems at 40mg/kg, and seizures at 60mg/kg. However, some dogs are more sensitive than average, so any chocolate consumption is potentially dangerous!
Can it be treated?
In the initial stages, before symptoms appear, emptying the offending animal’s stomach is generally effective at minimising the risk of poisoning. We can use drugs to trigger vomiting, but sometimes we have to pump the stomach out as well. We can then use activated charcoal to absorb any left-over toxin in the gut.
Once symptoms appear, we may try and use activated charcoal to reduce absorption, but the focus is in stabilising the heart and managing the seizures and fits. Once symptoms have started, affected animals usually need to be admitted for intensive care and stay in the hospital while we try to control the symptoms and keep them hydrated with intravenous fluids.
Fortunately, with prompt treatment, most affected animals will make a good recovery - but any delay can be life threatening.