Tuesday, September 27, 2011

something sweet

The vast majority of pet-owners and the general population already know that chocolate is toxic to dogs.  Have you ever wondered actually why it is toxic and the mechanisms behind what can be so delightful for humans (yum!) and so poisonous to our pets?

A friend recently asked me to provide the explanation, and I thought I'd share it with you all, as well.

Chocolate contains compounds called methylxanthines, specifically theobromine and caffeine.  Dogs are believed to metabolize these compounds differently than humans, resulting in toxicity.  (Chocolate also contains high amounts of fat and sugar, which can cause GI upset even in small ingestions). The amount of methylxanthine in chocolate depends on the type of chocolate; in general, the more bitter the chocolate, the higher the methylxanthine content.  Therefore, baker's chocolate is more toxic than dark chocolate which is more toxic than milk chocolate, with white chocolate containing the least of the compound.  Baker's chocolate is estimated to contain about 7 times more theobromine than milk chocolate.

If your dog ingests chocolate (or any other toxin), it is very important to call your veterinarian or an animal poison control center (888-426-4435) for specific recommendations.  Early intervention is key to a positive outcome, and calculations based on your dog's weight, type of chocolate, and amount ingested are key in treatment recommendations.   As with most poisons/toxins, do NOT wait for symptoms to start, the time for the best outcome is BEFORE symptoms occur!

 The amount ingested and the size of the pet determines the level of toxicity. A dog ingesting enough of even just milk chocolate can develop life threatening symptoms.

The mechanisms of action of these active compounds is to inhibit a receptor in the central nervous system, resulting stimulation and tachcyardia (elevated heart rates).  Symptoms occur depending on amount ingested compared to body weight of the patient.  Lower exposures can result in vomiting and diarrhea, usually just as a result of the high sugar and fat content of most chocolates.  Vomiting and diarrhea can become quite severe and require hospitalization for fluid therapy and symptomatic treatment.  Higher exposures can result in the symptoms attributed primarily to methylxanthines; agitation, restlessness, hyperactivity, as well as tachycardia, (dangerously high heart rate), arrythmia (abnormal heart beats). Some severe exposures can result in seizures or even death, especially if untreated.

The good news is that usually, dogs respond to treatment.  The best treatment is preventing access of your pet to any compounds or foods containing chocolate. The most common times of year for our ER to see a spike in chocolate toxicity cases are the days after halloween, easter, thanksgiving and Christmas. If a dog is seen ingesting chocolate, a calculation can usually be made to determine what level of ingestion has occurred.  If the ingestion is above a toxic level, a veterinarian will usually recommend an office visit to induce vomiting.   Vomiting should never be induced at home, as complications can occur (aspiration of vomitus, choking), and medications in the hospital are much more reliable in producing productive emesis than anything given at home. Depending on the level of ingestion, activated charcoal may be given by your veterinarian.  Hospitalization for IV fluids, heart monitoring, or other medications may be necessary.

 If the patient is already experiencing vomiting and diarrhea before the exposure is known or recognized, then the treatment depends upon severity of symptoms.  Many patients improve rapidly with hospitalization for Iv fluids, treatment of nausea, diarrhea, and prevention of hyperactivity or tachycardia.  

Bottom line - save the sweets for yourself, and keep your pets safe as we approach the holiday season!  I'll highlight some more common toxins in the upcoming blog posts.  More information is available at veterinary partner.com.


  1. Is white chocolate free of all the toxic compounds? I know it's not real chocolate, but it does contain cocoa butter.

  2. White chocolate is not free of all toxic compounds, but it does have a very significantly lower amount of them. That's why it takes so much more to cause the really nasty chocolate toxicity signs. Any amount can still cause vomiting and diarrhea, or pancreatitis, as it's a very rich food substance our pets aren't used to eating. I wouldn't recommend feeding it to your pet, but if they get into it, it's far less serious than bakers chocolate.