Dogs and chocolate do not mix

In December, dogs are more than twice as likely to scarf down a toxic dose of chocolate than at any other time of the year. This is probably because their human companions have stocked up on candies, cocoa and baking chocolate for gifts and treats. The harmful substances in chocolate are theobromine and caffeine. Cocoa powder contains the highest amount of caffeine and theobromine, followed by unsweetened baker’s chocolate, sweet chocolate and milk chocolate. White chocolate contains negligible amounts of methylxanthines and caffeine.

The most common clinical signs of chocolate toxicity are restlessness, hyperactivity, vomiting, diarrhea, increased drinking and urination, and a rapid heart rate. Animals may begin pacing and are unable to sit still. They may pant and appear anxious. Hyperactivity may progress to tremors and seizures if large amounts of chocolate are ingested.

In a study in England, nearly five times as many dogs ate chocolate in the week surrounding Christmas compared with other periods, beating out Easter, Valentine’s Day and Halloween. People give gifts of chocolate that are wrapped and put under the tree. What is a dog likely to say? “Oh, fabulous, a snack!” Dogs can smell right through the paper. Darker chocolates have grown increasingly popular; unfortunately, these darker chocolates contain more of the toxins.

For a dog, a deadly dose is about 100-200 milligrams per kilogram of body weight. That means that a 20-pound dog needs only 14 ounces of milk chocolate to kill it. About 3.5 ounces of semi-sweet or bittersweet chocolate could kill a 20-pound dog, and as little as one ounce of baker’s chocolate could end its life.

To treat chocolate toxicity, vomiting is induced and activated charcoal is administered to absorb any residual chocolate. Clinical signs are treated symptomatically and may require intravenous fluids, as well as medications to control hyperactivity, seizures and a rapid heart rate. In most cases, recovery occurs within 24-48 hours with appropriate treatment. With large amounts of chocolate ingested, cardiac arrhythmias and seizures can be fatal.


Dr. Karsten Fostvedt is a veterinarian at St. Francis Pet Clinic in Ketchum.

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