Yes, chocolate is toxic to dogs (and cats!). While rarely fatal, chocolate ingestion can result in significant illness. Chocolate is toxic because it contains a chemical called theobromine, as well as caffeine. Theobromine is the predominant toxin in chocolate and is very similar to caffeine. Both chemicals are also used medicinally as a diuretic, heart stimulant, blood vessel dilator, and a smooth muscle relaxant. Dogs cannot metabolize theobromine and caffeine as well as people can. This makes them more sensitive to the chemicals’ effects.
The amount of toxic theobromine varies with the type of chocolate. The darker and more bitter the chocolate, the more dangerous it is to dogs. Baking chocolate and gourmet dark chocolate are highly concentrated and contain 130-450 mg of theobromine per ounce, while common milk chocolate only contains about 44-58 mg/ounce. White chocolate barely poses any threat of chocolate poisoning with only 0.25 mg of theobromine per ounce of chocolate (that said, dogs can still get sick from all that fat and sugar, which can cause pancreatitis). To put this in perspective, a medium-sized dog weighing 50 pounds would only need to eat 1 ounce of baker's chocolate, or 9 ounces of milk chocolate, to potentially show signs of poisoning. For many dogs, ingesting small amounts of milk chocolate is not harmful.
Toxic doses of theobromine are reported to be as low as 20 mg/kg, where agitation, hyperactivity and gastrointestinal signs (such as drooling, vomiting, and diarrhea - all which may smell like chocolate) can be seen. At doses over 40 mg/kg, cardiac signs can be seen, and include a racing heart rate, high blood pressure, or even heart arrhythmias. At doses of more than 60 mg/kg, neurologic signs can be seen, including tremors, twitching, and even seizures. Fatalities have been seen at around 200 mg/kg (approximately 100 mg/lb), or when complications occur.
Clinical signs depend on the amount and type of chocolate ingested. For many dogs, the most common clinical signs are vomiting and diarrhea, increased thirst, panting or restlessness, excessive urination, and a racing heart rate. In severe cases, muscle tremors, seizures, and heart failure can be seen. In older pets that eat a large amount of high quality dark or baking chocolate, sudden death from cardiac arrest may occur, especially in dogs with preexisting heart disease. Complications (such as developing aspiration pneumonia from vomiting) can make the prognosis for chocolate poisoning worse. When in doubt, immediate treatment by your veterinarian is warranted if a poisonous amount of chocolate is ingested.
Clinical signs of chocolate poisoning can take several hours to develop, and can last for days, due to the long half-life of theobromine. The theobromine can even be re-absorbed from the bladder, so IV fluids and frequent walks to encourage urination may be necessary. It is important to seek medical attention by calling your veterinarian or Pet Poison Helpline* as soon as you suspect that your dog has eaten chocolate.
If you ever have a poisoning emergency there is a hotline you can call: the ASPCA Animal Poison Control Center, 888-426-4435. Their website is www.aspca.org/pet-care/animal-poison-control to see if a poisonous amount of chocolate was ingested. If a toxic amount is ingested, you should have your dog examined by us immediately. The sooner the theobromine is removed from the body or the dog is stabilized, the better your dog's prognosis.
© LifeLearn Inc.