From: http://www.aspca.org/site/PageServer?pagename=pro_apcc_news082106
dogs ingesting significant amounts of items sweetened with xylitol could develop a fairly sudden drop in blood sugar, resulting in depression, loss of coordination and seizures. “These signs can develop quite rapidly, at times less than 30 minutes after ingestion of the product. Therefore, it is crucial that pet owners seek veterinary treatment immediately.” Dr. Dunayer also stated that there appears to be a strong link between xylitol ingestions and the development of liver failure in dogs.
When she left her dog at the vet hospital, she was too weak to stand. I haven't heard any more news yet. It can take days for all the damage to become evident.
If you own a pet, you might want to make yourself aware of what in your environment is poisonous to your pet, and take steps to keep such things out of reach of your pets, or out of your house.
The ASPCA has a list of toxic-to-pets items. Most of this stuff I knew, but I didn't know about xylitol - that's a fairly recent chemical to appear on the scene, and I don't remember there being any real media blitz about the danger to critters. My friend asked me to post about this because I have more readers than she does, and she wanted get the information out to as many people as possible. Xylitol's toxicity to dogs is severe, and they've discovered that even small amounts can cause damage. The toxicity for cats is as yet unknown.
If your pet gets into something and you're unsure of the implications, contact your vet right away. If it's late and you need immediate assistance, you can call the ASPCA Animal Poison Control Center Hotline at 888-426-4435 (it's a $55 call).