Toxicity - Chocolate
Written by Dr. Peggy Root
The toxic compounds in chocolate are theobromine and caffeine, which are classified as methylxanthine alkaloids. Theobromine is the primary chemical involved in chocolate toxicity in small animals. Dogs and cats are exposed to chocolate especially during the holiday season. Because of their small body size relative to human beings, ingestion of a fairly small amount of chocolate may cause toxicity. As little as 4 ounces of baking chocolate or 1 pound of milk chocolate could be fatal if ingested by a dog weighing 10 pounds or less. Dogs will readily eat a toxic dose of chocolate. Ingestion of the rich smelling cocoa bean landscaping mulch also can be a cause of methylxanthine toxicity. The relative amount of theobromine contained in various chocolate compounds is described in the table below.
Theobromine is absorbed from ingested chocolate products slowly, reaching peak levels in the blood about 10 hours after ingestion.
Initial clinical signs are seen 2 to 4 hours after ingestion, and include restlessness, panting, vomiting, urinary incontinence, diarrhea and increased heart rate. Over time, the body temperature rises, arrhythmias of the heart occur, and the muscles become rigid. Finally, seizures and coma occur, followed by death.
Treatment involves decreasing further absorption of theobromine from ingested chocolate. Induction of vomiting only is beneficial if the animal is seen within 2 hours of having ingested the chocolate and if seizures have not begun. Chocolate products may coagulate into a ball in the stomach, preventing their expulsion or movement through the intestinal tract. Supportive care that will be provided by the veterinarian includes administration of intravenous fluids, medications as needed for heart abnormalities and seizures, and maintenance of normal body temperature. Because chocolate products generally are high in fat, secondary pancreatic disease may occur.
Prognosis for dogs with chocolate toxicity is good if the animal is treated by the veterinarian within 2 to 4 hours of their having eaten a toxic dose of chocolate. Prognosis is guarded if heart abnormalities or central nervous system signs, such as tremors, muscle rigidity, or seizures, develop.
Potential chocolate poisoning is an emergency. Please call your veterinarian. Do not leave e-mail messages on this site about possible poisonings, as messages are not answered swiftly enough to ensure your pet's safe recovery.
Emergency personnel at the University of Minnesota Veterinary Teaching Hospital can be reached at 612-625-1919 during the day before 4:30 pm, and at 612-625-9711 in the evening and on weekends.
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Gwaltney-Brant S. Toxicology of common household hazards. Proceedings, Midwest Veterinary Conference, Columbus OH, 2001;127-134.
Osweiler GD. Chocolate toxicity. In: The five minute veterinary consult, Canine and feline, Tilley LP and Smith FWK (eds), Williams and Wilkins, Philadelphia PA, 1997;440-441.