The main ingredient of Smecta is montmorillonite, which is used to treat diarrhea, but it is not suitable for cats. It will increase the burden on the cat's body. When the cat has diarrhea, you can feed it some probiotics to help regulate the stomach. If it does not improve, It is recommended to send the cat to a pet hospital for examination and treatment immediately to avoid life-threatening dehydration of the cat.