It's xylitol, an artificial sweetener extracted from birch trees. Here's a frightening quote:
A few sugar-free breath fresheners, a pack of gum, a spilled tin of mints, a sugar-free dessert cup. It takes only a little of this toxin to send a dog into hypoglycemia-induced seizures, and just a little bit more to bring on liver failure.It's in so many of our foods.
And it's in many medications!!
I think everyone should read what Dr. Patty Khuly says.
My personal rule is, beware of giving human foods to Penny! Check the label on anything, no matter how innocent it seems.
I shudder when I think of the advice I was given when she had a cough last year, to give her a children's cough elixir. I think it is very likely that it would have had xylitol in it.