Chocolate poisoning is a common problem in dogs. The signs can range from a simple stomach upset to life-threatening problems, depending on how much chocolate is ingested. Dark chocolate and baking chocolate are more poisonous than white chocolate.
What is chocolate poisoning?
Chocolate contains two ingredients that can be poisonous to pets - caffeine, and a chemical called theobromine. While dogs and cats are both very sensitive to the effects of caffeine and theobromine, cats are usually not attracted to chocolate, so chocolate poisoning tends to be less common in cats.
The amount of caffeine and theobromine in chocolate varies with the type of chocolate. The general rule is the more bitter the chocolate, the more caffeine and theobromine it is likely to contain. For example, unsweetened baking chocolate contains almost seven times more theobromine than does milk chocolate. White chocolate is also potentially poisonous but contains less caffeine and theobromine than milk chocolate does.
Cacao bean mulch contains enough theobromine to be poisonous if a dog or cat eats large enough amounts of it. Other products that contain caffeine include coffee, tea, and cola soft drinks. These should be withheld from pets as well.
How common is chocolate poisoning?
Animals of all ages are susceptible to chocolate toxicity affecting many organ systems
Cases of chocolate ingestion in dogs are common when chocolate and chocolate products are readily available in the home, eg Christmas, Valentine's Day and Easter.
Smaller breeds where quantity consumed relative to body weight may be greater.
Dogs with pre-existing cardiac disease and/or on theophylline medication.
What are the signs of chocolate poisoning?
Clinical signs of chocolate poisoning can begin to occur within an hour of ingestion. Caffeine and theobromine are both stimulants of the brain and heart, so the clinical signs can include hyperactivity, increased heart rate, muscle tremors, and potentially death. Other clinical signs include:
The chocolate smell on breath
Anxiousness, restlessness, and pacing
Complications associated with chocolate poisoning can lead to death within 24 hours of ingestion.
How is chocolate poisoning diagnosed?
Caffeine and theobromine can be detected in the stomach contents and blood of animals that have eaten chocolate, but a diagnosis of chocolate poisoning is usually based on evidence that the pet has eaten chocolate.
If chocolate ingestion is suspected, call your vet immediately! Based on your pet's weight and an estimate of the amount of chocolate eaten, your vet may be able to calculate the amount of caffeine and theobromine that was ingested and determine if your pet is at risk for a poisonous reaction. For example, if a large dog eats a few small pieces of milk chocolate, the amount ingested may not be enough to cause a problem. However, if a small dog eats one or two squares of bittersweet baking chocolate, this could be an emergency. Chocolate can have other dangerous components, eg macadamia nuts and raisins are also poisonous to animals, so tell your vet if the chocolate that your pet ate contained any other components.
How is chocolate poisoning treated?
As soon as you discover that your pet has eaten chocolate, contact your vet immediately. If your pet ingested enough chocolate to be dangerous, immediate treatment will be recommended. If the ingestion is detected early enough, your vet may be able to induce vomiting to clear the chocolate from the stomach before it gets absorbed. Further care, including hospitalisation for cardiovascular monitoring, may still be recommended. If ingestion occurred more than a few minutes ago, it may be too late to induce vomiting. Your vet may administer activated charcoal to your pet. This is a liquid or tablet that is given by mouth and limits absorption of anything in the stomach and upper intestines. Your vet may also recommend hospitalisation for administration of intravenous fluids (to help remove the chemicals from your pet's system) and for monitoring. Because caffeine can be reabsorbed by the bladder wall, keeping your pet's bladder empty can also help speed up recovery time. This is managed by frequent walking or by placing a urinary catheter.
How is chocolate poisoning prevented?
Dogs have a tremendous sense of smell and tend to be very curious about their surroundings. If there is chocolate in your home, there's a good chance that your dog will find it and eat it - leaving chocolate sweets on a countertop or on a coffee table puts your pets at risk. They will even knock trays of brownies or biscuits off the cooker and eat them. Make sure to keep all tempting chocolate treats away from your pets.
Other foods that can be dangerous to pets include raisins (which can cause kidney damage), macadamia nuts (which can cause muscle tremors and shaking), xylitol artificial sweeteners (which can cause low blood sugar, seizures, and liver failure), onions (which can cause anaemia), and uncooked bread dough (which can expand in the stomach and require surgical removal).
 C. F. Agudelo, Z. Filipejova and P. Schanilec, “Chocolate ingestion-induced non-cardiogenic pulmonary oedema in a puppy: a case report.,” Veterinarni Medicina, vol. 58, no. 2, pp. 109-112, 2013.
 N. Bates, P. Rawson-Harris and N. Edwards, “Common questions in veterinary toxicology.,” The Journal of Small Animal Practice, vol. 56, no. 5, pp. 298-306, May 2015.
 European Food Safety Authority (EFSA), “ Theobromine as undesirable substances in animal feed - Scientific Opinion of the Panel on Contaminants in the Food Chain,” European Food Safety Authority Journal, vol. 6, no. 9, p. 725, 2008.
 S. Gwaltney-Brant, “Chocolate intoxication,” Veterinarni Medicina, vol. 96, no. 2, pp. 108-111, 2001.
 M. F. Stidworthy, J. S. Bleakley, M. T. Cheeseman and D. F. Kelly, “Chocolate poisoning in dogs.,” The Veterinary Record, vol. 141, no. 1, p. 28, 5; Jul 1997.