Xylitol is a sugar alcohol used as a sweetener in many gums, candies, and baked goods. It is also appearing in some brands of toothpaste. Xylitol is a common sugar substitute providing sweetness without calories and it also has some dental antibacterial properties. This is all great news for humans, but it is not so magical for dogs.
In dogs, xylitol ingestion causes a rapid (usually within 30 min but it can take up to 12-18 hours) and severe increase in blood insulin with resulting hypoglycemia which can last up to 12-24hrs. Hypoglycemia typically lasts 6-12 hours but can last up to several days. This occurs because xylitol stimulates a stronger insulin release than glucose resulting in very low blood sugar and clinical signs of vomiting, diarrhea, weakness, ataxia, tremors and possibly seizures.
There have been no reports of cats experiencing xylitol toxicity, as cats do not seem to have the same problem of excessive insulin secretion as do dogs. There have been no reported deaths associated with those dogs that developed uncomplicated hypoglycemia. In the less than 1/1000 dogs who develop acute liver failure, the mortality rate is 70-80%. Hepatic failure, with destruction of the liver tissue, can occur within 9-72 hrs of ingestion at xylitol doses >1.0 g/kg. The pathogenesis of hepatotoxicity of xylitol is currently unknown but it may be secondary to ATP depletion or reactive oxygen species. For currently unknown reasons, most dogs that develop liver failure do not show evidence of hypoglycemia on presentation.
Mild elevations of ALT (few hundred) are not uncommon and thought to possibly be due to mild hepatocyte swelling. Concern for acute liver failure occurs when ALT levels are >1000 and increasing to >10,000 in 24-48hrs. It can take up to 3 days for liver values to increase. It is currently recommend rechecking liver values, Tbili, phosphorus, platelets and clotting times daily for 3 days in dogs that may have ingested a possible hepatoxic dose. Hyperphosphotemia is associated with a worse prognosis in one study. 4/5 dogs in acute liver failure with hyperphosphotemia died or were euthanized.
Toxic doses of xylitol:
0.15 - 0.4g/kg or 0.3-0.4 pieces of gum/kg can lead to hypoglycemia. Ingested levels > 1.0g/kg can lead to acute liver failure.
Baking xylitol contains 190g/ cup
Trident gum contains 0.2g/piece, other kinds of gum have 0.3-0.4g/piece up to 1-3 grams/piece. If the gum lists xylitol as first sugar assume xylitol amount is ½ total amount of sugar alcohol listed (if a gum has 2g sugar alcohols assume it has 1-2 g/piece). Determining the amount of xylitol in the gum ingested can be very frustrating since owners rarely know how many pieces the dog actually ingested.
Gabapentin liquid (300mg xylitol/ml) given at the standard dose can be toxic to dogs at doses of Gabapentin > 10mg/kg
Oral dental solutions should not be toxic at directed doses but can be dangerous if the concentrated bottle is ingested or a small dog drinks from a water bowl dosed for a large dog.
Xylitol is absorbed very quickly (within 20mins) so there may not be a need for vomit induction (here at DoveLewis we still do as long as dog is not clinical for hypoglycemia). If nothing else this may help you determine how much gum was ingested if you can count the pieces in the vomit. The xylitol molecule is very small and does not bind well to activated charcoal so there is no need to give charcoal for absorptive purposes. You may choose to give charcoal with sorbitol as a cathartic.
If the dog is hypoglycemic administer IV fluids with dextrose for 6-12 hours then discontinue dextrose and monitor blood glucose q2-4 hrs off of dextrose. Hepatoprotectants should be administered and include SAME, milk thistle, and acetylcysteine.
If a hepatotoxic dose was ingested, aggressive treatment for acute liver failure is recommended including IV fluids +/- dextrose, plasma transfusions, vitamin K, hepatoprotectants, broad spectrum antibiotics and GI protectants.