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Notes on Chocolate Toxicity in Dogs
by Bonnie Dalzell, MA

The following information is taken from: Kirk and Bistner's Handbook of Veterinary Procedures and Emergency Treatment (6th edition) (a very useful book):

Chocolate - active ingredient = theobromine:

  • The half life in the dog is 17.5 hours
  • The Toxic dose in the dog is 100-150 mg/kg.
    • A kilogram (kg) = 2.2 lbs.
    • A milligram(mg) = 1/1000 of a gram

So for a 50 ln dog a toxic dose would be roughly 2.2 grams (2200 mg) of pure chocolate.

However the concentration of theobromine varies with the formulation of the chocolate so:

  • Milk chocolate has 44mg/oz (154mg/100gm): toxic dose for 50 lb dog - 50 oz of milk chocolate.
  • Semisweet chocolate has 150 mg/oz (528mg/100gm): toxic dose for 50 lb dog - 15 oz of semisweet chocolate
  • Baking chocolate 390mg/oz (1365 mg/100gm): toxic dose for 50 lb dog - 5 oz of baking chocolate

Thus a dog eating one oz of baking chocolate would have to eat almost 3 oz of semisweet or 10 oz of milk chocolate to get the same dose of theobromine.

The theobromine in candies consisting of chocolate that is coated over some other substance - as in filled candies and chocolate coated dried fruits, etc will be more dilute than that in pure chocolate bars and solid chocolate candies.

Obviously the chocolate in milk chocolate is quite dilute and this is why many dogs can eat a piece here and there and seem not to show toxic effects, how many dogs would get ahold of 50 oz at a time? This is not true of the more concentrated forms however. Dr Sue Bank's experience was that she had two dogs, a 95 pound one and a 60 pound one. Thye got ahold of 2 one pound bags of Nestle's semi-sweet chocolate pieces (a bag each). The 95 pound dog survived but the 60 pound dog ingested a toxic dose.

The problem with feeding a dog milk chocolate as a treat is that it develops a liking for chocolate and since dogs do not seem to be as sensitive to bitter tastes as humans - it may then eat the more concentrated, and thus quite toxic, baker's chocolate if it gets a chance or it will consume a toxic amount of milk or semi-sweet chocolate if it can get into a improperly stored supply.

Treatment which is best administered by someone with medical training follows the same strategy as treatment for caffine overdose:

  • Support Respiration
  • Support cardiovascular function, control arrhythmias, control electrolytes and acid-base balance.
  • Control CNS excitation.
  • Emesis
  • Gastric lavage
  • Cathartic
  • Activated charcoal

Administration of an activated charcoal slurry is a major component of the treatment and needs to be administered by a veterinarian - it is not a home treatment.

This article is dedicated to the memory of my friend Sue Bank's Borzoi, Windhound's Jai Java.

In November of 1998 I received the following correspondence which I am reproducing with the permission of its author.

Hi Bonnie,

Our dog's name is Napa. She is just under 3 months old. She is a neutered female of unknown breed (we suspect she has some lab, pointer, and/or terrier). She weighs about 18 pounds. She is black with spots of white that look like she dipped her face and paws in white paint. Napa is really cute and very smart. She is also quite mischievous.

Napa ingested about 6 oz (half a package) of Nestle's semisweet chocolate chips. We discovered this at 11pm. While my wife called the animal emergency hospital, I searched the Internet for "dog ate chocolate." The first site I clicked on was an article on NetPet Magazine. The information in this article confirmed our suspicion that 6 oz of semisweet chocolate could be a toxic dose for a dog Napa's size. Minutes later the vet confirmed this and I confirmed our suspicion that 6 oz of semisweet chocolate could be a toxic dose for a dog Napa's size. Minutes later the vet confirmed this and I rushed Napa to the hospital. They induced vomiting and administered activated charcoal. At about 12:30 am she was released. The vet asked me to monitor Napa continuously for the next 12 hours or so. Her heart rate was high (250) and she was acting pretty wired. Her body temp remained normal and over the next few hours the heart rate slowed a little. Had her heart rate increased or her body temp risen I would have returned her to the hospital for IV fluids. Luckily, that wasn't necessary. She reminded me of a person who had too much coffee for the next 36 hours. Finally she calmed down and slept for an extended period of time. Now (4 days later) she is back to normal and already trying to explore more cabinets for goodies to eat!

I believe that the information in the article on Netpet Magazine helped save Napa's life. By realizing the severity of the situation, my wife and I were able to act quickly to get Napa professional help.

Sincere thanks from Napa's human family, Jackie (3rd grade), Cyndi, and Rich. Her animal siblings Mickey (6 yr. old Black Lab) and Merlot (rambunctious 6 month old male tabby kitten) are glad to have Napa back to normal.

   -Rich Sadowsky

We at NetPet Magazine are so happy that our article was of use to Napa and the Sadowsky family.

I am especially pleased that the article helped to prompt the Sadowsky's to seek veterinary assistance as choc toxicity is not something to be treated at home.

It should be noted that high doses of chocolate are also toxic to humans. Thus small children also need to be protected from access to   large   quantities of   concentrated   forms such as baking chocolate. For details you must check with your pediatrician or local poison control center.

The ASPCA maintains the
National Animal Poison Control Center Hotline at:

Note: There is a modest fee for the service to support the Animal Poison Control Center. In my opinion it is a reasonable fee. There is no reliable way to maintain a large information service purely by volunteers.

Americans often seem to feel that access to information and help is free. It is not. You may support it by taxes, as in public health departments, libraries and public schools. You may support it by donation as in private schools and National Public Radio and Public TV. You may support it directly by buying a book or paying a consultation fee. However there is no state stipend to the people who provide the information, they are responsible for earning a living and supporting themselves.

However it happens, knowledgable people need to eat and pay the heating bills also, and detailed knowledge requires the investment of a lot of time and effort, so it is not something that can be done in someone's spare time.

NetPet Magazine is an example in point. The site costs around $300 a year to keep on the internet and since there is little advertising income of any consequence there is no money to pay for editorial services and site updates.

As of October of 1999 we are happy to report that the online magazine is receiving corporate sponsorship from the exciting new web search tool The NepPet . Be sure to visit their site!

Somehow I need to earn an income to support editorial efforts on site, otherwise my web page creation efforts are consumed by my web page business, and there is no time to get down to the local medical library and obtain information to enhance and update the site's information base. I have fairly extensive contacts with experts who will write for the site for very reasonable fees, but they also need to obtain some compensation for their efforts to make it a regular committment..

If this site is as useful to you as a magazine that you purchase, consider sending us a donation. Checks should be made out to Bonnie Dalzell and sent to 5100 Hydes Rd, Hydes MD 21082.


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