Many scoopable cat litters contain bentonite clay and/or silica. The bentonite component of kitty litter, sodium bentonite is a naturally occurring clay mineral that is considered to be biologically inert when ingested. Silica is also a physically and chemically inert substance, and is a major component found in ordinary sand. Silica is also used as a moisture-absorbing agent in the little packets found in shoe boxes, medications and some foods. In our experience, pets ingesting small amounts of silica gel may develop only mild gastrointestinal upset, if any signs develop at all.
Cats may ingest small amounts of litter when grooming themselves after using the litter box, and these amounts pass through the digestive tract easily without problems. However, if an animal consumes a very large amount of litter (as can happen when a dog "cleans out" the litter box), gastrointestinal upset, constipation or, in rare cases, intestinal obstruction could potentially occur. In addition, consuming fecal material may cause bacterial-related gastrointestinal problems. It is a good idea to discourage your dogs from helping themselves to the litter box by placing it in an area that is out of their reach, but still accessible to your cat.
My friend recently told me that kitty litter containing silica is poisonous to cats. Is this true?
—Susan G.
Silica-based cat litter has recently been the subject of discussion on the Internet, with some claiming that it is toxic and causes respiratory illness in cats.
Silica is a physically and chemically inert substance and is a major component in ordinary sand. Silica has many uses, including as an absorbing agent in cat litter. It’s also used as a moisture-absorbing agent in those little packets found in shoe boxes, medications and some foods. In our experience, pets ingesting silica may develop only mild gastrointestinal upset—if any signs develop at all. Silica, therefore, is not considered to be toxic.
Many scoopable cat litters that contain silica are processed in such a way to remove as much of the fine dust as possible. If you find that you or your cat is particularly sensitive to airborne dust particles, you may wish to consider using an alternate form of litter.