Maness Veterinary Services

522 SW 27th Place
Newcastle, OK 73065



Chocolate is a mixture of cocoa beans and cocoa butter. It contains theobromine and caffeine, which are both classified as methylxanthines. Unfortunately, dogs are sensitive to the effects of methylxanthines.
Depending on the dose, methylxanthines can cause hyperactivity, increased heart rate, tremors, and potentially death. Other effects seen with chocolate overdose include vomiting, diarrhea, increased thirst,
increased urination, and lethargy.

The amount of methylxanthines present in chocolate depends varies with the type. The general rule is the more bitter the chocolate, the more toxic it could be. In fact, unsweetened baking chocolate contains almost
seven times more theobromine as milk chocolate while white chocolate (a combination of cocoa butter, sugar, butterfat, milk solids, and flavorings without cocoa beans) contains negligible amounts of methylxanthines.

Type of Chocolate



Milk chocolate


Baking chocolate







The mechanism of action of methylxanthines is to competitively inhibit cellular adenosine receptors which results in CNS stimulation and tachycardia.2 Although, theobromine and caffeine have an LD50 of 100 to
200 mg/kg, signs can be seen well below this dose.3 Mild signs can be seen at doses over 20 mg/kg, moderate effects are seen over 40 mg/kg, and severe effects are seen at doses over 60 mg/kg.3

Early treatment, including decontamination procedures such as emesis and activated charcoal, cardiovascular monitoring, and supportive care, is extremely helpful with chocolate poisoning. In addition, fluid diuresis may help enhance elimination 3 Caffeine can be reabsorbed by the bladder wall which may result in extended times of clinical signs. Therefore, the veterinary staff should take extra steps to keep the patient's bladder empty either through catherization or frequent walking