Xylitol is a popular sugar substitute made from a sugar alcohol. Although Xylitol is considered to be safe when used as a sugar substitute for people, it may cause hypoglycemia and acute death of liver cells in dogs.

Xylitol was first manufactured in 1891 by chemist Emil Fisher by hydrogenating a sugar found in wood. Xylitol is also found naturally in berries, lettuce and mushrooms. Xylitol has 2/3 the calories of sugar and is used as an equal measure substitute for sucrose. It is commonly seen in chewing gum, toothpaste, and more and more frequently as a sugar substitute in baked goods. Commercially available products include the trade names of Epic, Spry, Nicorette, and Trident. These lines include gums, breath mints, mouthwashes, and toothpastes.

Xylitol is absorbed slowly in people. In dogs, Xylitol is rapidly and almost completely absorbed within 30 minutes and causes a greater release of insulin than would occur with a similar dose of glucose. This results in hypoglycemia (lack of glucose concentrations in the blood). In the dog, hypoglycemia occurs approximately one hour after ingestion of Xylitol.

The onset of clinical signs is rapid. Vomiting is usually seen first. In 20% of cases, hypoglycemia develops within 30 to 60 minutes after ingestion. Clinical signs progress rapidly from being lethargic to becoming unbalanced, collapsing, hemorrhaging, and having seizures.

Blood work shows hypoglycemia, hypokalemia, hyperphosphatemia (low glucose, low potassium and high levels of phosphorous). Elevated liver enzymes occur 12 to 24 hours after ingestion. Bleeding problems will also occur and are exhibited by the inability of blood to clot, resulting in skin and gastric hemorrhages. Hyperphosphatemia is considered to be a poor prognostic indicator.

Dogs have been shown to suffer severe hepatic necrosis resulting in a loss of liver cells with a collapse of the liver’s architecture. The cause of the necrosis is unknown although several theories exist. The effect of Xylitol on cats is also unknown.

Other artificial sweeteners, such as saccharin (Sweet ’n’ Low), aspartame (Nutrasweet) and sucralose (Splenda) are generally regarded as safe and should not cause significant illness other than possible osmotic diarrhea.

Before the onset of clinical signs, emesis (vomiting) may be induced to bring up the offending substance. Activated charcoal may not be beneficial in preventing absorption of Xylitol since is so rapidly absorbed. If hypoglycemia develops, intravenous dextrose may be helpful in maintaining normal glucose concentrations. The hypokalemia may be treated by adding potassium to IV fluids. Liver protectants and antioxidants such as “Denosyl® and Marin®”, both manufactured by Nutramax, may be helpful in treatment although their efficacy in this Toxicosis has not been established. Blood transfusions may be necessary if bleeding develops.

If you get uncomplicated hypoglycemia or mild liver enzyme activity, the prognosis is good with supportive care. If severe liver enzyme elevation occurs, hyperphosphatemia or if bleeding develops, the prognosis is poor. In conclusion it is best to avoid all food items containing Xylitol in the dog.

Reference

1. Dunayer, EK, Ms. VMD, DABT, DABVT New Findings on the Effects of Xylitol Ingestion in Dogs, Veterinary Medicine December 2006, 791-796.