Sugar-free, but Not Risk-free
Sugar substitutes are big business. Less sugar can mean weight loss, improved health, diabetic control, and even reduced tooth decay. The quest for products that can sweeten and cook like sugar is ongoing. Xylitol is a common substitute, especially when it comes to gum. Not only does xylitol offer sweetness, but it has also been shown to reduce periodontal disease from its antibacterial properties. These are great, provided you are human. For dogs, xylitol is a potentially lethal.
In the canine body, the pancreas confuses xylitol with real sugar and releases insulin to store the "sugar." The problem is that xylitol does not offer the extra calories of sugar and the rush of insulin only serve to remove the actual sugar/glucose in the bloodstream. Blood sugar levels plummet resulting in weakness, disorientation, tremors, and potentially seizures. It doesn't take many sticks of gum to poison a dog, especially a small dog (see below). Symptoms typically begin within 30 minutes and can last for more than 12 hours. Vomiting and diarrhea can also occur.
The other reaction that can occur with xylitol in dogs is the actual destruction of liver tissue. How this happens remains unknown but the doses required to produce this effect are much higher than the hypoglycemic doses mentioned above. Signs take longer to appear (usually around 8-12 hours later) and surprisingly not all dogs that experience this hepatic necrosis will show hypoglycemia first. Internal bleeding is commonly involved.
The hypoglycemic dose of xylitol for dogs is considered approximately 0.1 grams per kilogram. A typical stick of gum contains 0.3-0.4 grams of xylitol, which means that a 10 pound dog could be poisoned by as little as a stick and a half of gum. The dose for liver failure is roughly 10 times this, so a 10 pound dog would have to eat an entire package of unopened gum, and this amount of gum would probably cause only hypoglycemia in an 80-90 lb. dog. (Note — the current gums that use xylitol are Dentyne Ice, Orbit, and Trident)
Treatment: Ideally, a patient can be seen quickly to induce vomiting. But if the ingestion has occurred at an unknown time and the dog is symptomatic, then a sugar IV drip if the proper course of action for 24 hours. Liver enzyme and blood clotting tests are monitored for 2-3 days as well.
So watch where you put that gum, even the ABC gum ("already been chewed") that your dog can get to in the trash. It just might save his life.
P.S. At this time, there are no reports of xylitol toxicity in cats.