Most kitty litter products are made out of organic materials
such as bentonite clay or silica. These substances are considered to be
chemically and biologically inert, and do not pose a toxic concern for pets.
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 ingests 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.