found this on a vet site :
SILICA GEL PACKS
Desiccant packs are included as moisture absorbents. They are found in shoe boxes, electronics, medications and food. Occasionally, desiccants might be used as an insecticide, particularly for slugs. Silica gel, one of the most common desiccants, is a white powder or a lustrous granule. Silica gel comes in paper packets or plastic cylinders. Packages of silica gel are attractive to pets because of the rustling noise, and the packages are easy to bat around. Most ingestions will not cause clinical signs, although a mild gastrointestinal upset may occur. If a large amount is ingested, there is potential for osmotic diarrhea occurring. In most cases, the packet will be ruptured and the contents ingested. Ingestion of the intact packet may cause a gastrointestinal obstruction.
http://www.ridgeanimalhospital.com/holidayHazards.htm