It's common knowledge that chocolate can be harmful to dogs. But chocolate's nothing compared to another ingredient found in many foods that's 12 times as dangerous to your pup — and you probably have never heard of it.
The Wall Street Journal reports that xylitol, a low-calorie sweetener found in chewing gum, toothpaste, mints, gummy vitamins, melatonin pills, and some peanut butters, is causing an uptick in emergency trips to the veterinarian. In 2004, vets reported 82 xylitol poisonings; in 2014, there were 3,727, with at least 11 dogs dying from the chemical.
When dogs eat xylitol, their insulin levels spike, which can cause seizures, brain damage, liver failure, and sometimes death. Usually your dog will be okay if you get it to the vet in time, but it depends on how much xylitol your pet has consumed. It's unclear how cats react to it, but it's actually beneficial to humans: Xylitol prevents cavities and tooth decay, which is why many dentists recommend chewing gum with xylitol in it on purpose. Specific gum brands that use xylitol include Trident and Ice Breakers.
Most food brands won't tell you how much xylitol they use in their products, but if it's listed as one of the first ingredients, make sure to keep it far away from your dog. (If you keep it in your house at all.) Some activists are calling for xylitol warning labels on packages, but until then, make sure you check the ingredient list on anything sugar-free. PreventiveVet has a full list of products that contain xylitol, which can include surprising things, such as facial cleansers and certain medications.