It's just another day at your house. You pull in to your driveway, park the car, and get out. Everything is as it should be... until you reach the door. You first notice that there is no barking greeting your key in the lock. As the front door swings open, you are overwhelmed by an awful odor--some foul degeneration of decency, a mixture of cat urine and something more organic. You drop your keys in horror, directly into a fresh puddle of vomit.

The cat is running back and forth. The dog is panting heavily. The bird is on his back on the floor of the cage. Fearing the worst, you look into the back. The horse has diarrhea.

What has gone so terribly wrong in this household? What sort of foul toxin has destroyed your loving home and all the animal life within it? The answer is somewhat shocking, and not for the weak of heart. Unfortunately, all of your animals are experiencing classic signs of theobromide poisoning. The insidious culprit?

Chocolate.

Chocolate, my sweet comfort? Impossible.

Chocolate, derived from the cacao bean, is rich in multiple compounds that are said to increase alertness, stimulate the central nervous system and vasculature, and release neurotransmitters that induce a sense of well-being. One of the main components in chocolate is theobromine, an aromatic compound that provides the bitter taste of chocolate products, especially those in purer forms. It's also a sassy fashion accessory. Caffeine is also a component of chocolate, but is found in much lower quantities in both the cacao bean and the derived products than its methylxanthine friend. It may still have negative effects when ingested, contributing to toxicosis symptoms.

As stated, chocolate is known to induce somewhat beneficial and perhaps even pleasant experiences when consumed by humans. This is due to the fact that humans are capable of efficient theobromine breakdown once it has been absorbed into the body. This is not the case with most animals. Theobromine has an extended half-life when ingested by most common pet species, because they do not have the ability to clear the substance quickly or effectively. This is unfortunate, as the long half-life and stimulatory effects of the chemical can cause an uncomfortable and potentially deadly toxicity.

Fluffy had a little snack. How will I know if she's sick?

Animals that have ingested chocolate or chocolate-like substances, such as cocoa powder or even cacao-bean mulch, will begin to exhibit signs somewhere around 6-10 hours after consumption. These signs arise in the central nervous system, respiratory system and cardiovascular system. There are also some renal implications of toxicity.

Early signs, or signs of a mild toxicity, include:

Later, or more severe symptoms may include:

If left untreated, symptoms may progress to coma and death. Death is usually due to cardiac dysfunction, respiratory failures, or hyperthermia.

For science-minded individuals, please check the Merck Veterinary Handbook for a more detailed description of how and why these things occur.

It killed my horse! How much of this stuff is lethal?

I don't actually know the lethal dose for a horse, a cat, a chinchilla, or most other animals. Theobromine poisoning has been most studied and documented in dogs, and the toxic-to-lethal dose is around 100-200 mg/kg, although toxicities have been noted to begin at levels as low as 20 mg/kg. The source of this information is somewhat questionable, but it is not unlikely that individual tolerance has a large amount of effect on the level required to cause toxicosis. Toxicity problems have been reported in many animals, including most common household pets. This includes dogs, cats, ferrets, and birds. Birds appear to be more susceptible to chocolate toxicity than other animals. This may be due in part to their small size, or perhaps to their ridiculously efficient digestive systems.

Due to the dose-dependent nature of the toxicity, body size will play a large role in how much chocolate an animal can tolerate before its body begins to crap out. Small animals are at a much larger risk, due to the fact that it takes so little to make up the lethal dose for them. Strangely enough, rats and mice are not much affected by theobromine (even straight) or chocolate products in general. A study conducted showed evidence that rats escape the common symptoms shown by other animals, but face the unfortunate side effect of male sterility. Females were unaffected, although the babies of pregnant females treated with theobromine were somewhat small. Keep this in mind if you have no pets-- perhaps you can leave out chocolate chips as an eco-friendly rodenticide.

The type of chocolate also makes a big difference in toxicity of the substance. Chocolates that are the most pure are the most likely to cause toxicity, as they have higher concentrations of theobromine than their more sugary compatriots. Cocoa powder and baking chocolate are the most toxic, with theobromine levels of roughly 390-450 mg per ounce. Semi-sweet chocolate has a content roughly half that (195-225 mg/oz) and milk chocolate has about 44-60 mg/oz. White chocolate has a negligible amount of both caffeine and theobromine. It would take about two times a dog's body weight in white chocolate to cause any adverse effects, and it's probable that a dog that ingested that much of anything would be having a lot more to worry about than a little poisoning.

All these numbers, in layman's terms, means that a 5-pound (2.27 kg) chihuahua can ingest 21.26 g (0.75 oz) of milk chocolate before entering mild gastrointestinal distress, but will be in a critical state if only 0.2 oz (5.67 g) of baking chocolate is consumed. A typical bar of Hershey's baking chocolate is 28 grams. A larger dog can ingest much more. Both dogs are at risk because a larger dog is likely to eat more, and much more quickly, equalizing the playing field rather easily. It also means that your Lab eating 3 M&M's is no reason to rush to the emergency vet. For a Yorkie? Perhaps. Personally, I found that my 12 pound dog cannot, in fact, metabolize an 8 ounce bag of hot cocoa mix. She could, however, ingest 16 ounces of cappuccino with no adverse effects.
For a complete description of toxicity levels per body weight, please look to the links below. You can also find the amount of theobromine in commonly found chocolate products, courtesy of the Hershey corporation.

Well, there's no doubt the chocolate was eaten. What now?

In most cases where chocolate toxicity is feared, the best way to prevent symptoms is to induce vomiting. This is done within 1-2 hours of ingestion, and never after onset of severe symptoms. This can be done by a trained veterinary professional, or by dosing your pet with hydrogen peroxide. Let's face it though-- you should probably take your pet to the doctor if you're really nervous about what is going to happen. In the hospital, they may be treated with real emetics and placed on supportive care.

There is no real antidote for toxicity. Instead, animals are placed on IV fluids to replace water lost due to vomiting or diarrhea. They may have to treat the animal with activated charcoal to stop further absorption of theobromine. It is important to note that your pet will probably continue to vomit after having their stomach pumped. Factor this in to your plans if you have a white carpet. We did not. For severe cases, anti-seizure or cardiac medications may be administered to counteract the negative effects of those symptoms.

Prognosis following chocolate toxicity is generally fairly good, depending on the severity of the toxicity. Obviously, those animals that experienced severe symptoms such as seizure or arrhythmia are at greater risk for adverse problems in the future than animals with lower intake and less serious reactions. Early treatment and supportive care are critical in preventing things from reaching these dangerous levels.

So there you have it. As people grow more and more fond of cocoa-based desserts, and as chocolate-driven holidays approach, it becomes important to watch where you keep your candy. A little bit can go a long way in causing you a lot of heartache and carpet cleaners.


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Just for trivia's sake, I figured I would keep a running tally of the things my dog(s) have consumed that they shouldn't have. To date, my puppy has had:
  • one 8 oz. bag of hot chocolate mix
  • 2 bags of cappuccino mix
  • 1 bar souvenir chocolate
  • approx. 15-20 Viactiv calcium supplement chewables
  • 4 Cadbury eggs
  • 1 12 oz box Hershey's Hugs and Kisses
  • 5 oz. of Nestle Crunch Bunny
  • approx. 2 oz Kahlua Mudslide with an extra double shot of Baileys Irish Cream. Here, the alcohol was more concerning than the chocolate/coffee
  • 1 Godiva Praline Truffle, purchased after a bad day for a pricey $1.50 and later puked on the carpet. The white carpet.
The danger inherent in eating these things is generally not illness, but a real fear I will put them through a fucking wall.

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