by Franc von Esse, VMD, DABVP – Chief of Emergency & Critical Care; Director of Emergency Services
Chocolate ingestion and toxicity is a common problem in the emergency room. Though many people are aware that chocolate can be a problem for dogs, most people do not know the why, the how, and the how much. There are also some misconceptions about what types of chocolate is most problematic.
Dogs get into chocolate all the time in spite of our best efforts. However, there seem to be two times of the year when the frequency of cases increases: around Halloween and around Easter.
A class of compounds called methylxanthines are the active “toxins” in chocolate. Caffeine is an example of a methylxanthine. The main compound in chocolate is theobromine, though chocolate contains small amounts of caffeine as well. Methylxanthines work, through a variety of pathways, to open airways, increase heart rate and cardiac muscle contraction, increase alertness, and are a general stimulant to the central nervous system. People who drink coffee certainly seek these effects. Some types of methyxanthines are also used therapeutically, but the therapeutic range for these drugs are narrow and at high doses these effects can lead to vomiting, high blood pressure, irregular heart rhythm, agitation and hyperactivity, tremors and even seizures.
There are several reasons why chocolate is well tolerated by people and more problematic in dogs. First, size plays a role. Most adults, and even children, weigh more than many of our dogs. The other issue is that dogs metabolize theobromine much more slowly than people. The half life of theobromine in people is about 6-8 hours, in dogs it is 17.5 hours (over double). Another reason is that dogs, once they get into some sort of chocolate product, tend to eat everything that is available. Our labradors are not very good at self regulating.
Different types of chocolate contain vastly different concentrations of theobromine. See the table below for some examples. Note that the more sugar (or dairy) in the product, the lower the concentration of theobromine.
Product Theobromine Concentration
- Dry Cocoa Powder 800 mg/oz
- Baker’s Chocolate 450 mg/oz
- Semi-sweet Dark Chocolate 260 mg/oz
- Sweet Dark Chocolate 160 mg/oz
- Fudge (recipe dependent) ~ 50 mg/oz
- Milk Chocolate 45-65 mg/oz
- Chocolate Covered candy < 20 mg/oz
Signs are dose dependent. In general, doses of less than 20 mg/kg cause no ill effects. Cardiac signs are expected at doses of 40-50 mg/kg. More serious effects are expected when doses exceed 60 mg/kg. Potentially fatal doses are experienced at doses greater than 100 mg/kg.
Something to keep in mind is that once we get to things like milk chocolate, fudge, and chocolate candies (candy bars and the like), many of the adverse effects are more commonly related to the amount of sugar and fat in the products. Large quantities of sugar and fat pull large amounts of fluid in the body into the stomach, result in thirst (many dogs will drink whole bowls of water then vomit). These animals may experience “food bloat,” a syndrome in which the stomach is stretched out due to ingested material and fluid. Other potential complications can include potentially complications like diarrhea or even pancreatitis.
If your dog does get into chocolate or any type of chocolate product there are several things to do. First, as with any emergency, stay calm. Contact us or your family vet: we can figure out the degree of danger and what actions should be taken. Treatment options include induction of emesis, decontamination, stomach decompression (“stomach pumping”). In more significant exposures, hospitalization, monitoring, and in patient therapy may be advised.