What's fiction, what's true?

Feb 3, 2007 11:04 GMT  ·  By

A handful of chocolate drops should kill a small dog like a chihuahua, as it is often said.

But many owners offer chocolate to their canine pets, so: Is chocolate truly poisonous to dogs?

Dogs have similar tastes to humans, and like us, they are sweet tooth.

But while humans can ingest safely big quantities of chocolate, dogs metabolize theobromine more slowly, that's why chocolate triggers them theobromine poisoning.

The theobromine will remain in the dog's bloodstream for up to 20 hours.

"The hazard, however, is probably overblown," says Tim Hackett, a veterinarian at Colorado State University.

Chocolate's effects are linked to its quantity and quality and the dog's size.

The chocolate's poison is the alkaloid called theobromine, whose molecules bind to receptors on the surfaces of cells and block the natural compounds that normally attach there.

In humans, theobromine provokes the release of the euphoria hormone, serotonin but in dogs low doses trigger vomiting, nausea, increased urination or diarrhea.

If a large amount of theobromine or caffeine is ingested, some dogs will present muscle tremors, cardiac arrhythmias, epileptic seizures, internal bleeding, heart attacks and can even die.

Theobromine can make a dog's heart race up to twice its normal rate, and some dogs may run around as if "they drank a gallon of espresso," according to Hackett.

Bitter chocolate contains six times more theobromine as milk chocolate, but theobromine's levels also varie with cocoa beans strain as well as different brands of chocolate.

Less than four ounces of milk chocolate is potentially deadly for small dogs.

A 20 kg dog will normally present intestinal distress after eating less than 240 g of dark chocolate, but won't necessarily present heart impairments unless it consumes at least a half a kilogram of milk chocolate.

Just 1.3 g of bitter chocolate per kilogram of a dog's body weight is enough to trigger poisoning (so just 25 grams of unsweetened chocolate will poison a 20 kg dog).

In 16 years, as an emergency and critical care veterinarian, Hackett has witnessed just one dog death from chocolate poisoning, and he suspects it may have had an underlying disease rendering it more vulnerable to chocolate's effect.

Poisoned dogs are generally treated by inducing vomiting within two hours after ingestion and administering activated charcoal to absorb any theobromine remaining in the gut or that may be circulating through the dog's digestive system.