Toxicology Tuesday, August 14

"My dog ate ..." I don't know how many times in my career someone has started a conversation with those three words. Well, today, my dog ate ... chewing gum.

Help me, quick! Is it ...

Toxic or Not?

Answer:

Up until quite recently, my response to “My dog ate gum” would have been “No worries. Everything will come out all right in the end,” but not any more. Now, I double-check what kind of gum we are talking about. As astute readers noted, the key ingredient here is xylitol, which is TOXIC to dogs.

Orbit and Spree are two examples of xylitol-containing products, and I just found sugarless Trident and Altoids gum, both with xylitol, in my local grocery store. At least Trident prints it in big letters on the front of the package; most of the time, it is in tiny writing on the back or an end, hard to find even if you are looking.

Xylitol is a sugar alcohol found in many sugar-free products, including gum, mints, chewable vitamins, oral care products, and in a granulated form used for baking.

"Natural" does not always equal "safe."

Long popular in Europe, xylitol is only recently coming into wide-spread use in the USA. Xylitol has been touted as a miracle product for people. Not only is it as sweet as sucrose (table sugar) with two-thirds the calories, but also is a good sugar-substitute for people on low-carb diets. It is particularly beneficial as an energy source for people with diabetes, since it doesn’t require insulin to enter the cells. Xylitol has even been shown to prevent the growth of certain bacteria, making it useful to prevent cavities and in treatment of bacterial otitis media (middle ear infection) in children.

Despite its many virtues for humans, xylitol can be deadly in dogs. The first reported effect was to cause a sudden and severe drop in blood sugar, as xylitol stimulates the release of six times more insulin than would be expected from an equivalent amount of sugar. The resulting hypoglycemia leads to lethargy, weakness, ataxia (incoordination), collapse, and seizures. Hypoglycemia may show up within 30 to 60 minutes of ingestion, or may be delayed for up to 12 hours.

More recently, xylitol toxicity has been associated with acute liver toxicity and with impaired blood clotting ability. Eight dogs with this syndrome were reported to the ASPCA’s Animal Poison Control Center between 2003 and 2005, and five of the eight died or were euthanized for liver failure.

The toxic dose of xylitol is 0.1 gm/kg body weight, while liver failure results from doses greater than 0.5 g/kg body weight. Translating these numbers into something usable in the every-day world is a little harder to do, since the amount of xylitol varies from one product to another. Two sticks of gum is enough to cause a serious drop in blood sugar for a small (under 20 lb) dog, while it might take 8 to 10 sticks to affect a large (over 60 lb) dog, but these amounts are only an estimate. As for baked goods containing xylitol, again, the amount in each cookie or muffin will vary. In one case, a Standard Poodle died after eating 5 or 6 cookies sweetened with xylitol.

There are a number of other sugar substitutes (saccharine, aspartamine) including sugar alcohols (sorbitol, mannitol) but so far, only xylitol has been found to cause such severe and life threatening injury.