With Easter right around the corner, it’s that time of year again when we like to overindulge on one of our favourite foods: chocolate. Unfortunately, that also means it’s the time of year when we see chocolate toxicity in our beloved dogs.
Theobromine and caffeine are the main compounds in chocolate that cause toxicity. If a dog consumes a low dose of these substances, they will vomit and have diarrhoea. They may also begin to drink and urinate excessively. This can cause them to be generally unwell and can eventually lead to dehydration. At higher doses, their heart rate will increase and they can become hyperactive which can lead to elevated body temperatures (hyperthermia). Muscle tremors/spasms, seizures, heart arrhythmias and cardiac arrest can then follow, which will lead to death in a very short time.
The toxic dose for chocolate in dogs is surprisingly small and depends on the size of the dog, the amount of chocolate eaten and the type of chocolate. The more bitter the chocolate, the higher the concentration of theobromine and caffeine. Therefore, cooking and dark chocolate are the most toxic types of chocolate. White chocolate doesn’t contain a lot of these toxins, however it is still high in sugar which can upset their stomachs. Baked goods (such as chocolate cake or chocolate icing) that contain cocoa powder can also be toxic to dogs. As little as 5g of dark chocolate in a small dog can cause a severe reaction.
If your dog has eaten any chocolate at all, it is important to contact your local vet or emergency centre as soon as possible. The first thing that they will do is to induce your dog to vomit. This is to reduce the amount of toxins that can be absorbed and hopefully reduce the severity of the toxicity. It is not recommended that you induce vomiting at home. Many of the home remedies for vomiting can also be fatal to dogs, so it is important that this procedure is done by a veterinarian. The ongoing treatment will vary depending on the severity of the signs displayed. Hospitalisation and intravenous fluid therapy to flush their system of the toxins are generally required.
While chocolate toxicity is fairly well known by dog owners, there are some other toxicities that we also see at this time of year that aren’t as well publicised. Grapes, sultanas and raisins (especially chocolate coated raisins!) are highly toxic to dogs.
The first signs of a grape or raisin toxicity are vomiting, anorexia and diarrhoea. Dogs often become lethargic and may show signs of abdominal pain and these signs can go on for days to weeks. The most deadly part of this toxicity is its effects on the kidney. It is unknown at this stage exactly what the toxin is and how it causes its effects, however clinically we see the kidneys become damaged and then stop functioning entirely. This results in little to no urine production, a build up of waste products in the patient’s bloodstream and ultimately death.
As the exact toxin is unknown, the toxic dose of grapes/raisins hasn’t been determined at this stage. There are reports that as few as 4 or 5 grapes have caused the death of an 8kg dog.
Treatment of these cases can be difficult. If your dog has recently eaten grapes, you should contact your local vet or emergency centre as soon as possible. As with chocolate toxicity, the first thing that is done is to induce vomiting to remove as much of the toxin as possible. Activated charcoal may be administered to try and reduce the absorption of the toxin as well. Blood testing, hospitalisation and aggressive intravenous fluid therapy is often required for these patients and the prognosis can be guarded to poor depending on the severity of signs.
Another important toxin to dogs that is found in human foods is xylitol. Xylitol is an artificial sweetener found in many different foods and products, such as toothpaste, vitamin tablets/gummies, chewing gum, peanut butter, sugar-free lollies and fruit drinks. While it is not toxic to humans (and some studies are showing that it has a range of beneficial health effects for humans) it is highly toxic to dogs.
There are two main ways that xylitol causes toxicity in dogs. Because it is an artificial sweetener, a dog’s pancreas will mistake xylitol for real sugar. The pancreas responds to normal sugar intake by releasing insulin so the sugar can be stored in the body. The problem is xylitol doesn’t have the calories that sugar does and the insulin release just reduces the real sugar levels in the bloodstream. This causes the blood glucose levels to drop very quickly which causes vomiting, weakness, incoordination and disorientation, tremors and even seizures. Signs can begin within half an hour of ingesting a product containing xylitol and may last for greater than twelve hours.
The other problem with xylitol is it will destroy the liver cells in dogs. This takes longer to happen then the blood sugar drop and can vary in severity from a short period of being unwell to acute liver failure which can lead to death. The liver is a very important organ and is responsible for detoxifying the body and the production of important substances such as clotting factors. Often severe cases will have internal bleeding as the liver cannot produce clotting factors. At this stage we do not know exactly how xylitol causes liver damage.
A dose of 75-100mg/kg of xylitol is enough to cause low blood glucose levels in dogs, and a dose of 500mg/kg can cause liver damage. One piece of gum that contains 1g of xylitol is enough to cause toxicity to a 10kg dog.
If you are concerned that your dog has eaten a product containing xylitol, it is important to contact your local vet or emergency centre as soon as possible. If they have only recently eaten the product, vomiting will be induced. Blood tests to check glucose levels and liver function will be performed and then most patients will be hospitalised on a glucose infusion and continually monitored for at least a 24hr period, depending on the severity of the signs. Often repeat blood tests will be required over the next few days and symptomatic therapy given as required.
These are just a few of the common toxins found in human foods. The main goal is to avoid our beloved canines ingesting them at all as prevention is much better than a cure in these cases, particularly as we don’t have antidotes to the majority of toxins. Hopefully, both you and your dogs have a wonderful Easter holiday that is emergency free!
