Both my cats are in good health but throw-up almost every day. They are not eating plants...

One of the most common reasons that a cat might regurgitate are hairballs. In some cases feeding the cat a diet such as Purina ONE Advanced Nutrition Hairball Formula can help prevent the formation of hairballs before they start. If vomiting is chronic, it is always advisable to have a veterinary examination to rule out any other possible intestinal problems.



Source: http://www.purinaone.com