# Why Does Chocolate Harm Dogs, But Not Humans? **URL:** \ **Category:** Factual Questions\ **Created:** [March 13, 2005, 5:01pm UTC](https://boards.straightdope.com/t/why-does-chocolate-harm-dogs-but-not-humans/294346 "2005-03-13T17:01:58Z")\ **Posts on this page:** 10\ **Page:** 1
**Author:** ![ricksummon](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ricksummon/32/3333_2.png) [@ricksummon](https://boards.straightdope.com/u/ricksummon)\ **Post date:** [March 13, 2005, 5:01pm UTC](https://boards.straightdope.com/t/why-does-chocolate-harm-dogs-but-not-humans/294346/1 "2005-03-13T17:01:58Z")
Everyone knows that chocolate (specifically, the chemical theobromine) is toxic to dogs, yet is harmless to humans. My question is, what specific biochemical difference between humans and dogs makes this happen? ---
**Author:** ![Duckster](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/duckster/32/1244_2.png) [@Duckster](https://boards.straightdope.com/u/Duckster)\ **Post date:** [March 13, 2005, 5:37pm UTC](https://boards.straightdope.com/t/why-does-chocolate-harm-dogs-but-not-humans/294346/2 "2005-03-13T17:37:07Z")
> [@](#): > > Theobromine belongs to a class of alkaloid molecules known as methylxanthines. Methylxanthines naturally occur in as many as sixty different plant species and include caffeine (the primary methlyxanthine in coffee) and theophylline (the primary methylxanthine in tea). Theobromine is the primary methylxanthine found in products of the cocoa tree, theobroma cacao. > > – snip – > > Cocoa and chocolate products may be toxic or lethal to dogs and other domestic animals such as horses because these animals metabolize theobromine more slowly than humans. The heart, central nervous system, and kidneys are affected. Early signs of theobromine poisoning in dogs include nausea and vomiting, restlessness, diarrhea, muscle tremors, and increased urination or incontinence. The treatment at this stage is to induce vomiting. Cardiac arrhythmias and seizures are symptoms of more advanced poisoning. Source: [Molecular Facts and Structures](http://chemistry.about.com/library/weekly/aa090301a.htm) See also … > **[Is chocolate poisonous to dogs?](https://animals.howstuffworks.com/pets/question348.htm)** > > My dog really likes chocolate, but my mother won't let me feed it to him. She says it will kill him. Does that make sense? If I can eat chocolate, why can't my dog? [http://www.envtox.ucdavis.edu/cehs/TOXINS/dogs.htm](http://www.envtox.ucdavis.edu/cehs/TOXINS/dogs.htm) [http://ask.yahoo.com/ask/20000607.html](http://ask.yahoo.com/ask/20000607.html) ---
**Author:** ![Scott\_Plaid](https://avatars.discourse-cdn.com/v4/letter/s/258eb7/32.png) [@Scott\_Plaid](https://boards.straightdope.com/u/Scott_Plaid)\ **Post date:** [March 13, 2005, 6:33pm UTC](https://boards.straightdope.com/t/why-does-chocolate-harm-dogs-but-not-humans/294346/3 "2005-03-13T18:33:43Z")
Chocolate is proof the IPU (Blessed be her hoves) loves us and wants us to be happy. She is not, however, a dog lover. ---
**Author:** ![samclem](https://avatars.discourse-cdn.com/v4/letter/s/a9a28c/32.png) [@samclem](https://boards.straightdope.com/u/samclem)\ **Post date:** [March 13, 2005, 6:51pm UTC](https://boards.straightdope.com/t/why-does-chocolate-harm-dogs-but-not-humans/294346/4 "2005-03-13T18:51:47Z")
**Scott\_plaid**. This is General Questions. In general, we want posts to be contributing to answering the OP. We do allow some latitude, and a funny now and then is overlooked. But, having said that, you’ve racked up warnings in Great Debates. Let’s not make it a habit over in GQ. I’d seriously look at my posting style, if I were you. Enough warnings, and you could be out of here. Just saying… **samclem** GQ moderator ---
**Author:** ![Scott\_Plaid](https://avatars.discourse-cdn.com/v4/letter/s/258eb7/32.png) [@Scott\_Plaid](https://boards.straightdope.com/u/Scott_Plaid)\ **Post date:** [March 13, 2005, 6:54pm UTC](https://boards.straightdope.com/t/why-does-chocolate-harm-dogs-but-not-humans/294346/5 "2005-03-13T18:54:18Z")
I’ll be good. ---
**Author:** ![MaryEFoo](https://avatars.discourse-cdn.com/v4/letter/m/ba8739/32.png) [@MaryEFoo](https://boards.straightdope.com/u/MaryEFoo)\ **Post date:** [March 13, 2005, 8:28pm UTC](https://boards.straightdope.com/t/why-does-chocolate-harm-dogs-but-not-humans/294346/6 "2005-03-13T20:28:23Z")
From **Duckster** , > [@](#): > > Cocoa and chocolate products may be toxic or lethal to dogs and other domestic animals such as horses because these animals metabolize theobromine more slowly than humans. Uh-oh, does that mean frequent doses of theobromine are bad for humans? Single observation: subject has about 1.5 tsp of black cocoa every morning in the form of choc. drink with milk, sugar, & vanilla. Subject has had no indisputable symptoms from the list in Duckster’s citation. Subject also consumes other chocolate, less that one day out of 10. When does subject die? (For extra credit, guess who is subject.) ---
**Author:** ![CrazyCatLady](https://avatars.discourse-cdn.com/v4/letter/c/dfb087/32.png) [@CrazyCatLady](https://boards.straightdope.com/u/CrazyCatLady)\ **Post date:** [March 13, 2005, 9:05pm UTC](https://boards.straightdope.com/t/why-does-chocolate-harm-dogs-but-not-humans/294346/7 "2005-03-13T21:05:20Z")
Subject dies when something else kills her. Or when you eat an entire canister of baking cocoa for breakfast. Frequent doses of moderate amounts of chocolate aren’t harmful, because we break them down long before they can build up toxic levels of theobromine. It’s a matter of total amount in the body at any given time, not how much you’ve had sum total over an extended period. That said, it typically takes a whopping lot of milk chocolate to kill a dog. The LD50 for that particular form is something like an ounce per pound of body weight. Dark chocolate and baking chocolate, however, are far more concentrated and so the LD50 is far lower. I’m wanting to say that baking chocolate is something like an eighth of an ounce per pound of body weight, but I don’t really remember. (I don’t check that part of the chart very often, because baking chocolate’s bitter and dogs typically don’t eat it.) ---
**Author:** ![Washoe](https://avatars.discourse-cdn.com/v4/letter/w/ecae2f/32.png) [@Washoe](https://boards.straightdope.com/u/Washoe)\ **Post date:** [March 13, 2005, 9:09pm UTC](https://boards.straightdope.com/t/why-does-chocolate-harm-dogs-but-not-humans/294346/8 "2005-03-13T21:09:42Z")
My veterinarian and I were discussing this a few months ago, and she told me that theophylline is only part of the picture, and that it is actually a lesser component of chocolate’s toxicity to dogs. She said that there is a another chemical in chocolate which is even more insidious. Unfortunately, I can’t remember exactly what she told me, but the gist of it is that feeding chocolate _even once_ to a dog can cause them to develop a fatal blood disease _as much as five years later!_ I think she said that is some sort of hemolytic anemia. I have to go see her sometime within the next couple of weeks to refill a prescription, so I’ll ask her again, and this time I’ll write it down and report back here. ---
**Author:** ![Ethilrist](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/ethilrist/32/4604_2.png) [@Ethilrist](https://boards.straightdope.com/u/Ethilrist)\ **Post date:** [March 13, 2005, 9:24pm UTC](https://boards.straightdope.com/t/why-does-chocolate-harm-dogs-but-not-humans/294346/9 "2005-03-13T21:24:07Z")
Something else to watch out for in addition to actual chocolate: nurseries sell cocoa-hull mulch which is just as toxic, but perhaps not as tasty. If your neighbors are in the habit of using this stuff, you might want to keep your dogs clear of their yards… ---
**Author:** ![richardb](https://avatars.discourse-cdn.com/v4/letter/r/96bed5/32.png) [@richardb](https://boards.straightdope.com/u/richardb)\ **Post date:** [March 14, 2005, 2:52am UTC](https://boards.straightdope.com/t/why-does-chocolate-harm-dogs-but-not-humans/294346/10 "2005-03-14T02:52:15Z")
Some facts: [Chocolate Toxicity](http://www.marvistavet.com/html/chocolate_toxicity.html) Not a whole lot, but answers to some questions asked here, including: > [@](#): > > Toxic doses of theobromine are 9 mg per pound of dog for mild signs up to 18 mg per pound of dog for severe signs. Milk chocolate contains 44 mg/ounce of theobromine while semisweet chocolate contains 150 mg/ounce, and baking chocolate contains 390 mg/ounce. > > It takes nearly 4 days for the effects of chocolate to work its way out of a dog’s system.