Xylitol is an artificial sweetener often found in products like chewing gum. Xylitol doesn’t usually have adverse affects on humans but for dogs, it can cause their blood sugar to plummet. Dogs can then develop deadly seizures and these symptoms may not develop for anywhere from 30 minutes to several hours after consuming xylitol. Take your dog, if you suspect it to have eaten xylitol, to a vet immediately.