Xylitol is a sugar alcohol — an artificial sweetener created from birch, raspberries, plums and corn.
This sweetener is found in many human "sugar free" products, such as gum, candies and other sweets. In humans, high doses may have a mild laxative effect, but in dogs, ingestion could be fatal.
It has been known for quite some time that there is a link between xylitol ingestion and hypoglycemia (low blood sugar) in dogs. Now, with the prevalence of this sweeter in human foods, the ASPCA Animal Poison Control Center has noted a connection between xylitol consumption and acute toxicity in dogs.
Xylitol has also been suspected of causing toxicity in ferrets.