Bodie Stutz, sporting a costume chosen by Sandy Vaillancourt, is ready for trick or treaters this year.

photo courtesy of Kami Michels

How can something so good cause so much trouble? I'm talking about chocolate, currently on the top-10 list for poisonings in dogs. Cats, more discriminating in what they eat, are usually not affected. Typically, the history involves a dog who gulped down an entire bag or two of delicious Halloween treats, wrappers and all. He seems fine initially, other than the sheepish look on his face. But chocolate is a potentially deadly toxin, and significant ingestion requires immediate and thorough treatment.

The toxic agent in chocolate is Theobromine, which acts a bit like a super caffeine dose. It causes an increase in skeletal and cardiac muscle activity, hyperresponsiveness to environmental stimuli, restlessness, panting, vomiting, diarrhea, tremors, ataxia, excessive urination, and, terminally, seizure, coma, and heart failure. Because the half-life of Theobromine in the body is 72 hours, treatment is usually an extended process.

How much is too much? Chocolate poisoning charts give some guidelines, but it is very individual, and depends on whether your dog is sensitive. Some dogs regularly eat small amounts of chocolate without ill effects, whereas others will become seriously ill after just an ounce or two. Baking chocolate is the most dangerous, followed by dark chocolate and then milk chocolate. The amount of Theobromine in different brands of chocolate can also vary, so I tend to err on the side of caution and treat all chocolate ingestion as potentially serious.

If your dog gulps down your Halloween goodies, the first step is to induce vomiting, ideally within the first few hours. Hydrogen peroxide is a common household ingredient for inducing vomiting. Call your veterinarian first for a dosage based on your dog's size, and advice on whether your dog needs to be seen immediately. The idea is to get most of the chocolate out of the body before it is absorbed. DO NOT try to induce vomiting in a dog already showing muscle tremors or hyperexcitability, as this may result in choking or vomitus in the lungs, causing a new problem, aspiration pneumonia.

After induction of vomiting, treatment has two goals. Gastric lavage and charcoal administration may help to reduce the amount of Theobromine that is absorbed. Supportive care will help to mitigate the toxic effects of the product that is already in the body.This typically involves IV fluids to flush toxins and stay ahead of dehydration, treatment for shock, and sedation or muscle relaxants to control seizures or hyperexcitability. Remember that Theobromine has a half life of 72 hours, so treatment will likely be for a few days. Death can occur within 12-36 hours, so don't wait until after the kids are done trick or treating to attend to this.

As always, prevention is the best medicine. Even the most well-behaved dog may get caught up in the holiday atmosphere and be tempted to counter surf or help herself to that jack-o-lantern bowl by the front door. After Halloween, be careful your goblins don't leave their loot laying around the house; the consequences for your pet can be scary indeed!

Dr. Cathy Theisen is a house call veterinarian in Ann Arbor, with 24 years experience in small animal medicine and surgery. Visit her website at www.cathythevet.net, or e-mail questions/comments to cathythevet@comcast.net.