The vomiting center of cats is very developed, so just a little stimulation can cause the cat to vomit. There are generally three methods to induce vomiting in cats. The first one is to pour soapy water or concentrated salt water into the cat to stimulate the cat’s stomach. A vomiting reaction will occur; second, feed the cat cat grass, which can also stimulate the cat's stomach and cause the cat to vomit; third, touch the cat's throat or the base of the tongue with your fingers or other soft objects , the cat will vomit immediately.