Each holiday season, veterinarians witness an increase in accidental chocolate poisoning in dogs. The majority of pet owners do not realize the potential for intoxication that chocolate possesses. Theobromine, caffeine and theophylline are all naturally occurring molecules that are found in several foods, plants, beverages and human and veterinary medications. Based on the number of calls received by The National Animal Poison Control Center and the Rocky Mountain Poison and Drug Center, one of the most commonly encountered poisonings in pet dogs is theobromine, or chocolate, poisoning. Theobromine comes from the plant Theobroma cocoa and is present in chocolate, cocoa beans, cocoa bean hulls, cola and tea.
Milk chocolate is obtained from seeds of theobroma cacao after fermentation and roasting.
However, serious non-fatal poisonings have been reported in dogs after eating smaller amounts. Deaths due to theobromine have been documented in horses who ate cocoa bean hulls used in bedding and in other livestock fed cocoa waste products. No chocolate poisonings have been reported in cats, which is probably a reflection of their eating habits. The the first signs of chocolate poisoning are vomiting and diarrhea, increased urination and nausea. These can progress to cardiac arrhythmias and seizures.