Why Are Chocolate & Onions Bad for Dogs?

Many dogs will eat just about anything, but just because something looks good to your pup doesn't mean it's good for it. In fact, foods that people enjoy can have serious health consequences for pets. Some can be fatal. Chocolate can cause dogs to have seizures, and onions can cause red blood cell damage. If your dog ingests either of these foods, determine how much he ate and call your vet immediately.

  1. Toxic Ingredients of Chocolate

    • Chocolate contains methylxanthines such as theobromine and caffeine, both of which are toxic to dogs. Toxicity is on a progressive scale: the darker the chocolate, the higher the toxicity. Therefore, baking chocolate is the most harmful to dogs, and white chocolate the least harmful. Any form of chocolate may be hazardous, including baked goods such as brownies, candy and pure cocoa powder. According to the ASPCA, 1 oz. of chocolate per 1 lbs. of the dog's body weight is potentially lethal.

    Symptoms of Chocolate Intoxication

    • Symptoms of chocolate intoxication begin to appear six to 12 hours following consumption. Symptoms may include vomiting, diarrhea, excessive thirst and urination, panting and restlessness. The dog may also be hyperactive and have an abnormal heart rhythm. Tremors and seizures may also occur and advanced signs include cardiac failure, weakness and coma. According to the ASPCA, death as a result of chocolate intoxication is usually caused by respiratory failure or cardiac arrhythmia.

    Toxic Ingredients of Onions

    • Onions contain thiosulphate which can cause gastrointestinal irritation as well as hemolytic anemia. This anemia causes the breakdown of the red blood cells and hinders oxygen delivery to the dog's muscle tissues. A decrease in blood pressure may also occur. Garlic and chives are also hazardous for dogs for similar reasons. The ASPCA states that small amounts of these ingredients as found in commercial dog foods may not be a problem; however, large amounts should be avoided.

    Symptoms of Onion Intoxication

    • Symptoms usually occur within 24 hours of consumption but may take several days to appear. They include shortness of breath, rapid heart rate, intolerance for cold, weakness and disinterest in exercise. The dog may also seem depressed, stop eating, and have diarrhea or abdominal pain, or have breath that smells of garlic. A vet will confirm an intoxication diagnosis with blood tests.

    How to Keep Your Dog Safe

    • Do not feed your dog table scraps that contain onions. Keep chocolate away from your dog. If you find a ravaged box of chocolate Valentine's candy, call your vet immediately.