Today I found out why chocolate is bad for dogs.

Chocolate contains an alkaloid called “theobromine”. Theobromine is in the same family as caffeine and is a type of stimulant (they both are mythylxanines). Theobromine stimulates the central nervous system, cardiovascular system, and causes a slightly increases blood pressure.

Dogs and certain other animals, such as horses and cats, cannot metabolize theobromine as quickly as humans can; this causes the above effects to be much more severe than is the case with humans. The specific notable side effects of toxic levels of theobromine in dogs includes: diarrhea; vomiting; increased urination; muscle twitching; excessive panting; hyperactive behavior; whining; dehydration; digestive problems; seizures; and rapid heart rate. Some of these symptoms, like the rapid heart rate, can ultimately be fatal to the dog.

So how much chocolate is too much for a dog? That depends on the size and age of the dog, as well as what type of chocolate was consumed. The larger the dog, the more theobromine they can handle without dying and older dogs tend to have more problems with the side effects, as noted above.

As far as the chocolate itself, cocoa powder contains about sixteen times as much theobromine per ounce over milk chocolate, with most popular forms of chocolate falling somewhere between those two, excepting white chocolate, which contains insignificant amounts of theobromine per ounce, making it extremely unlikely to be able to be consumed in sufficient quantities to harm a dog.

For more specific figures, here are the approximate amounts of theobromine per ounce of chocolate:

Cocoa powder: 800 mg/oz

Baker’s chocolate (unsweetened): 450 mg/oz

Dark chocolate: 150 mg/oz

Milk chocolate: 50 mg/oz

So, the general rules for the amount of chocolate that will be toxic for a dog:

Milk chocolate: one ounce per pound of body weight (so, without intervention, a 16 pound dog (7.2 kg) would likely die from eating one pound of milk chocolate)

Dark chocolate: 1/3 of an ounce per pound of body weight (around 5 ounces of dark chocolate for that same 16 pound dog)

Baker’s chocolate: 1/9 of an ounce per pound of body weight (around 1.8 ounces of baker’s chocolate for a 16 pound dog)

Cocoa powder: 1/16 of an ounce per pound of dog (around 1 ounce of cocoa powder to kill a 16 pound dog)

On the other extreme end, it would take about 200 pounds of white chocolate consumed within a 17 hour period to reach toxic levels of theobromine for a 16 pound dog. The low quantity of theobromine here is because white chocolate is made from cocoa butter, sugar, and milk, but no cocoa solids.

How to Treat a Dog That Has Eaten Chocolate

There is little that can be done for the dog, particularly at home, to treat the theobromine poisoning once it’s in the dog’s bloodstream. Thus, the general methods of treatment tend to be ways to try to stop the consumed theobromine from reaching the bloodstream. These include:

Inducing vomiting in the dog immediately, which helps remove much of the chocolate. After that, try to get the dog to eat a small amount of activated charcoal, which binds to the theobromine and keeps it from entering the bloodstream. Try to get the dog to consume as much water as possible to keep them hydrated. At the vet, certain drugs can be used to help the dog survive, such as anti-convulsants, which can help if the dog is having seizures.

In order to induce vomiting, the easiest way, aside from sticking your finger down their throat or the like, which isn’t at all recommended, is to get the dog to eat something like 1-2 tsp of hydrogen peroxide, which should shortly induce vomiting and can be repeated a few times every 15 minutes, if it does not. Alternatively, 2-3 tsp of Syrup of Ipecac should do the trick, though this one should NOT be repeated, even if it doesn’t work the first time.

For the activated charcoal, about 1-2 tsp of activated charcoal mixed thoroughly with water should be fed to the dog. This also works well for certain other types of toxins that dogs and cats can sometimes consume, such as: carbamate insecticides, herbicides, and rodenticides.

Bonus Facts:

Once the theobromine is in the dog’s bloodstream, the half-life is around 17.5 hours, so 24 hours or so after the dog has consumed the chocolate, if it is still alive, it’s probably going to make it.

Cats also are particularly susceptible to poisoning from chocolate for the same reason dogs are. However, unlike dogs, cats generally aren’t particularly inclined to eat chocolate, having no “sweet” taste receptors.

Horses can consume much more theobromine than dogs, despite how toxic it is for them oz/kg, due to their much higher weight. Theobromine has been used in the past to boost a horse’s performance, which is why it is banned in horse racing.

Theobromine can also be found in the leaves of the tea plant and the cola nut.

Human’s metabolize theobromine much faster than dogs, but sufficient quantities of this compound over a short enough time span can also induce similar toxic effects as can be found in dogs, though this is rare as the quantities required are much higher. However, theobromine poisoning can sometimes be observed in elderly people who eat excessive amounts of chocolate on a daily basis.

Human’s consuming caffeine will introduce theobromine into the body due to the fact that caffeine is metabolized in the liver into about 10% theobromine.

The earliest documented case of the cacao tree being cultivated is around 1100 BC in South and Central America.

It isn’t entirely known where the word “chocolate” came from, though it was introduced in English via Spanish. The popular theory, though not without credible competition, is that it was introduced to Spanish from the Nahuatl word “chocolātl”. Nahuatl was the language of the Aztecs. This word, in turn, derives from the Nahuatl “xocolātl” from “xococ”, which means “sour or bitter”, and “ātl”, meaning “water or drink”. The Aztecs particularly were known to make a “bitter drink” from cocao beans, which is where the above name came from.

Around 50 million people in the world depend on cocoa as their source of livelihood.

Around 2/3 of the world’s cocoa is produced in West Africa, largely by child labor.

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