In the world of sugar substitutes, we have all been accustomed to products with Nutrasweet, Sweet 'N Low (and other saccharins), Equal, and most recently Splenda. However, the December 2006 issue of the journal Veterinary Medicine cited the potentially toxic effects of the sweetener xylitol. The article was written by Dr. Eric Dunayer, staff veterinarian for the ASPCA Animal Control Center in Urbana, Ill. His article served as an educational tool for veterinarians and the dog-owning public.

Xylitol is a sugar alcohol used as a sweetener in many products, including sugar-free gum, chewable vitamins, oral care products and baked goods. While xylitol consumption is considered safe in people, dogs can develop serious, even life-threatening signs from its ingestion. Ironically, the symptoms brought on by xylitol do not mimic hyperglycemia (like in diabetes), but rather the opposite effects (hypoglycemia).

Xylitol's popularity is based on the fact that on a measure-for-measure basis, it carries only two-thirds the calories of sugar and causes very little insulin-release in people. Therefore, xylitol is viewed as a solution in the diets of many sweet-craving Americans.

How does that work? In simple terms, xylitol doesn't require insulin to enter cells, and therefore blood level concentrations of glucose are significantly lowered. The consequence in xylitol-sensitive dogs is that hypoglycemia can result from so much storage of glucose in the cells.

The sensitivity of xylitol in dogs has been documented by the ASPCA's Poison Control Center database from 2003-2006. Eight cases have illustrated that very small amounts (less than 0.1 gram per kilogram of body weight) can cause symptoms in dogs. Furthermore, it has been shown that serum glucose concentrations can dip in as soon as one to two hours after ingestion. Therefore, if symptoms of weakness and lack of energy are seen in your dog after sweet goodies are eaten, seek veterinary assistance.

Since the swing effect of xylitol toxicity is low blood sugar, veterinary care consists of intravenous dextrose administration until vital signs and glucose levels have normalized. Inducing vomiting or trying to absorb the substance via activated charcoal (like in the case of many other toxin treatments) is not useful in these cases.

The liver could also be impacted within 12 to 24 hours of the hypoglycemic episode, so veterinarians tracking the blood glucose levels need to also keep tabs on the liver enzymes. As an adjunctive therapy, liver protectants and antioxidants can assist with healing the potentially damaged livers in these dogs.

As a general veterinary practitioner, I have to step back and look at the preventive side of this discussion on xylitol. Since we see many overweight dogs in America today, and we veterinarians preach basic nutrition with quality dog food as the best policy, perhaps the statement needs to be made: Don't feed your dog any type of sweet goodie in the first place. After the news about xylitol, now at least you have one more reason not to.

Dr. Chris Duke is a veterinarian at Bienville Animal Medical Center in Ocean Springs, Miss. Questions for this column are encouraged. Write to: South Mississippi Veterinary Medical Association, 20005 Pineville Road, Long Beach, MS 39560, and include a self-addressed stamped envelope.