Chocolate toxicity is a very common problem in the world of pet medicine. The ubiquity and ease of accessibility of this globally revered foodstuff means that chocolate is a killer. Here's why:
Chocolate's main ingredient is an extract of the cocoa bean known as cacao, which contains two compounds that are toxic to dogs: theobromine and caffeine. Of the two, dogs seem to be much more sensitive to theobromine, a compound that stimulates the nervous and cardiovascular systems adversely and compromises the gastrointestinal tract as well. Caffeine is less well tolerated in dogs than it is in humans but it does, again, appear to be far less of a concern than the theobromine itself.
Dogs who ingest chocolate can either be so severely affected they succumb to its effects or so mildly affected that their owners never become aware their pets have been exposed. It's also been determined that some dogs are more susceptible to the effects of theobromine.
The difference between chocolate's more severe signs and its benign manifestations depends largely on the dose of cacao ingested. Hence, why smaller patients are more susceptible to its ill effects. This also explains why veterinarians always ask a) how much? and b) which kind? so that we know how best to treat our patients.
It should be noted that an emerging area of concern for dogs involves exposure to cocoa mulch, a byproduct of the chocolate industry and a significant source of theobromine. This product, sold at gardening supply stores, is to be avoided by dog owners who allow their pets unrestricted access to their yards.
Symptoms and Identification
The clinical signs of chocolate toxicity depend on the dose of theobromine the patient has received and the individual patient's degree of sensitivity to it. While some dogs react adversely to doses as low as 20 mg per kg, most require about 100 mg per kg to show clinical signs.
Nonetheless, there are some well-accepted chocolate dose calculators that can help pet owners determine whether their dogs require emergency treatment. But this can be tricky given that different types of chocolate offer differing amounts of theobromine.
For example, here are the following levels of theobromine in a variety of "chocolate" products (per ounce):
Dry cocoa powder: 800 mg
Unsweetened chocolate: 450 mg
Cocoa bean mulch: 255 mg
Semisweet chocolate: 150-160 mg
Milk chocolate: 44-64 mg
It bears noting that, as a rule of thumb, the following tend to hold true:
With milk chocolate, any ingestion of more than 0.5 ounces per pound of body weight is risky.
Ingesting more than 0.13 ounces per pound of body weight of dark or semi-sweet chocolate can cause significant signs that should be treated.
Almost all dogs exposed to unsweetened chocolate should be treated as an emergency.
White chocolate is considered an insignificant source of theobromine.
The following are the most commonly reported signs of exposure to chocolate, in order of increasing severity:
Increased heart rate
Increased blood pressure (generally mild)
Nausea and vomiting
Cardiac arrhythmias (abnormal heart rhythms)
The more severe signs tend to last for 24 to 48 hours post-exposure. Some of the less severe gastrointestinal symptoms may persist for up to several days or even a week or more.
Diagnosis of chocolate toxicity tends to rely primarily on evidence that the pet has ingested it. However, poisoning from this source can often be inferred from the clinical signs listed above.
The following tests and procedures may be undertaken as part of the diagnostic process:
CBC (complete blood count)
Chemistry (biochemical screen)
The EKG, in particular, may need to be repeated many times post-exposure to be sure pets are recovering adequately.
There is no known breed predisposition to the toxic effects of cacao. However, a genetic predisposition to greater sensitivity is presumed to play a significant role.
Pets who ingest excessive amounts of chocolate typically require a three-pronged treatment protocol:
Induce vomiting. This is especially effective if the chocolate has been ingested within the previous hour but vomiting can be induced up to two hours post exposure.
Provide general supportive care. There is no known antidote to theobromine. This means that all chocolate toxicity patients must be treated supportively. Most pets hospitalized for supportive care post-ingestion receive the following as part of their supportive care regimen:
Intravenous fluid administration and electrolyte support.
Sedatives to calm patients.
Activated charcoal (to reduce absorption of the chocolate and speed its transit through the gastrointestinal tract).
Gastroprotectants (drugs to support the GI tract).
Pro- and prebiotics to help reestablish normal bacterial colonies post exposure.
Urinary catheterization may also be required to help keep patients from re-absorbing theobromine via their own urinary bladders.
Provide specific cardiovasculatory or nerulogical support.
Drugs to slow the heart rate and limit dangerous heart rhythms may be required.
Anticonvulsants to limit seizure activity may be needed
Sadly, some pets may succumb in spite of treatment. The prognosis tends to be most poor for those who require specific cardiovascular or neurologic support, as described above.
The cost of toxic exposure to chocolate is typically not especially high if the patients arrive within an hour after exposure or if the degree of exposure is deemed mild. (Typically less than $300 to $500.) If intensive care is required, however, several thousands of dollars may be needed to support a patient through such a crisis.
Chocolate intoxication is 100% preventable. When pet owners take simple steps to manage their pets' exposure to chocolate and its byproducts, chocolate toxicity can be successfully mitigated.
Gwaltney-Brant S. Chocolate intoxication. Vet Med 2001;96:108-111.
Gwaltney-Brant, Sharon (February 2001). "Chocolate Intoxication". Veterinary Medicine Publishing Group. Retrieved November 5, 2011.
H. Gans, Joseph. "Effects of short-term and long-term theobromine administration to male dogs". Elsevier Inc. Retrieved 1 March 2012.
Johnston, John J. (2005). "Evaluation of Cocoa- and Coffee-Derived Methylxanthines as Toxicants for the Control of Pest Coyotes". Journal of Agricultural and Food Chemistry. Retrieved July 28, 2009.