Chocolate is one of the most common toxicities I see, especially around Christmas and Valentine’s Day. Pets climb counters to get to candy dishes and desserts. They also rip open boxes of chocolates wrapped as gifts. One of my patients, a cocker spaniel, ate a 5 pound box of dark chocolate that was left under the tree. They found him unconscious on his doggy bed.
Chocolate contains caffeine and theobromine which are toxic to animals. This fact surprises a lot of people because humans are fairly resistant to this class of drugs. We can drink a lot of coffee and eat chocolate without too many problems. But dogs are much more sensitive to the effects of these chemicals. The half life of caffeine in dogs is 4.5 hours while the half life of theobromine is 17.5 hours!
The amount of these two chemicals varies with the type of chocolate. Milk chocolate contains the least amount of caffeine and theobromine while the bitter chocolate used in cooking contains the most. Dark chocolate falls in between. The general rule that I was taught in veterinary college is the more bitter the chocolate, the more of these chemicals and the greater the danger of poisoning.
Clinical signs of chocolate toxicity depend upon the amount of theobromine and caffeine ingested i.e., the type and amount of chocolate and the size of the pet. A golden retriever who steals a dark chocolate candy bar may show no signs of toxicity whereas a Chihuahua may develop seizures. In general, signs of mild toxicity include an increased heart rate and hyperactivity which many people wrongly attribute to the sugar high. After the initial rush, some dogs will develop gastrointestinal signs including vomiting and diarrhea. Others drink and urinate excessively. Dogs who ingest large amounts of chocolate often seizure and may die.
Treatment of chocolate toxicity usually starts with ‘decontamination’ which means removing the toxin. If the dog is conscious, vomiting is induced to get rid of as much of it as possible. After the stomach is empty, the dog is given charcoal to absorb the remaining chocolate once they have stopped vomiting. The rest of therapy is tailored to the patient. Seizures are treated with anticonvulsant medications, life threatening ventricular tachycardia is slowed with heart drugs such as lidocaine or propranolol and stomach ulcers are given gastrointestinal protectants. The cocker spaniel mentioned above spent 3 days in the hospital on IV fluids and anticonvulsant therapy. For the first day, diarrhea poured out of his anus. It looked and smelled like chocolate. He was one of the lucky ones. Unfortunately, he still liked chocolate. His family said he managed to grab a brownie about a week after his ordeal.
If your pet ingests chocolate, contact your veterinarian or the Pet Poison Helpline right away. Have the type of chocolate, quantity of chocolate and weight of the pet ready when you call. The number for Pet Poison Helpline is: 800.213.6680. More helpful information on poison of all kinds can be found at www.petpoisonhelpline.com.
-Shell, Linda. “Xanthine Toxicosis” VIN Associate, Lasted updated 1/17/2006.