Dog - Chocolate Poisoning

What is chocolate poisoning?

Chocolate contains an alkaloid called theobromine which has an effect similar to caffeine. This drug is used as a diuretic (to preduce dilute urine), heart stimulant, vasodilator (to dilate blood vessels), and also smooth muscle relaxant but it can be poisonous in excess and some dogs appear to be particularly sensitive.

Surely the dog would have to eat a huge quantity of chocolate for this to happen?

Not necessarily. Toxic doses are reported at about 100 mg/kg body weight with fatalities at around 200 mg/kg. The amount of theobromine in chocolate depends on the type of chocolate.

Cooking chocolate and good quality dark chocolate contain between 15-20 mg/gram whereas popular milk chocolate only contains about 1.5 mg/gram.

Thus a small Chihuahua only weighing say a couple of kilos would have to eat less than 2 oz (50g) of good chocolate to potentially show signs of poisoning. Even a dog the size of a Labrador could die if it ate two or three 200g. bars of good quality or cooking chocolate.

What are the signs of chocolate poisoning?

Depending on the quantity actually eaten and the health status of the dog, sometimes no signs are apparent and the dog will be found dead from heart failure. This is particularly likely to happen in older dogs with cardiac (heart) problems. The usual signs are a thirst and urinary incontinence, vomiting, diarrhoea, panting, sometimes muscle spasms and seizures followed by coma and death. Excitability and a rapid, irregular heart beat are not uncommon.

What should I do?

If you have any suspicion that your dog has eaten an excessive quantity of chocolate, consult us without delay.

How soon do the signs occur?

Again, it depends upon the quantity of theobromine actually ingested. One of the problems with chocolate poisoning is that signs are often delayed for more than 12 hours. Another problem is that once absorbed theobromine can sometimes remain active in the body for over 24 hours without being excreted. Death following ingestion of fatal doses typically occurs about 24 hours afterwards.

What is the treatment?

This obviously depends on the clinical signs and the amount that may have been ingested. If the dog is presented to us early enough, simple emetics to make the dog sick may be all that are necessary. If there is doubt, we will administer activated charcoal which limits the absorption of the theobromine from the gut. The charcoal may be repeated every four hours for 24-36 hours since one of the problems with theobromine is that it circulates in the bloodstream and can exercise its effects over a relatively long period. This effect has been shown to be shortened by repeated charcoal administration. In addition we will admit the dog and administer intravenous fluid therapy (a drip) for at least 24 hours. Even if showing no signs it is essential that the dog is kept under close observation for at least 24 hours to check for any heart abnormality.

If chocolate is so poisonous to dogs why are doggy choc drops sold as treats?

The amount of theobromine in chocolate products varies widely as already mentioned.

Milk chocolate has relatively small amounts and dogs would have to eat a lot of milk chocolate to poison themselves. Dog chocolate has even less and therefore is considered safe to use as treats. It is important to keep in mind they are treats and use in moderation.

Is it true that other products from the cocoa plant can be poisonous?

There have been recent reports of deaths involving dogs that have eaten cocoa shell garden products. These are used similar to bark as a mulching product. Cocoa powder itself can be hazardous if consumed as has happened in some cases.