Everyone knows of the household materials and plants that commonly poison pets: chocolate, antifreeze, poinsettia leaves, oleander.

However, some recently discovered poisons are less known, including xylitol, a naturally occurring sweetener.

Xylitol is commonly used in sugar-free gum, beverages, pharmaceuticals, toothpastes and mouthwash, among other products. It is naturally found in many fruits and vegetables, but it is commercially produced from birch and other hardwood trees, wood chips and corn cobs.

Sugar-free gum is the most likely source of poisoning for dogs, but a recent report in the Journal of the American Veterinary Medical Association reported a dog poisoned by four large muffins sweetened with xylitol.

The dose required to cause problems for a pet varies. There may be a factor of individual susceptibility as well. In any case, no dog should be allowed access to xylitol-containing materials.

What should you do if you suspect your pet has eaten xylitol? First, call your veterinarian or emergency hospital immediately. Experts there will help you determine whether your pet is at risk.

Signs of toxicity may begin with evidence of low blood sugar. Dogs who ingest xylitol release massive amounts of insulin because xylitol is about four times sweeter than sugar, and the pancreas responds proportionately. Evidence of hypoglycemia includes weakness, tremors and seizures. Hypoglycemia does not occur in all victims and occurs two to four days later in some victims.

Like most species, dogs can experience gastrointestinal signs: vomiting and diarrhea. But, unlike other animals, dogs who have ingested sufficient amounts of xylitol, or individuals who are sufficiently sensitive to it, will experience liver damage and anemia. The damage to the liver may be mild or severe. Those who survive initially may show icterus (jaundice, yellowing of the eyes and skin), bilirubinuria (red urine which may be confused with blood in the urine, caused by breakdown of red blood cells in circulation), loss of appetite and extreme lethargy. Bleeding may occur as a result of damage to clotting factors in the body.

If these signs are not quickly addressed by your pet’s doctor, they can be immediately fatal, or leave your pet with liver damage that my shorten his life and require lifelong liver support.

Many patients do survive with aggressive therapy. An individual dog’s reaction to xylitol may be idiosyncratic, with some dogs minimally affected, other dogs mortally affected, and every scenario in between.

If you use sugar-free gum, or other xylitol-containing foods in your home, keep them securely out of reach of your dog. In a recent case at our hospital, a standard poodle searched in his owner’s purse until she found the gum, then ate the whole pack. She presented with gastrointestinal signs, and the owner thought the gum might have obstructed the GI tract.

Her initial GI signs, icterus and liver damage resolved sufficiently to bring her liver test results back into the normal range, though it’s not clear how much the liver may have been permanently damaged and may shorten her life as a result.