Foamy white vomit is a sign that a cat is hungry and suffering from a build-up of stomach acid, notes AssistFeed. The phenomenon is known as bilious vomiting and occurs in cats and kittens. It is easily prevented by breaking up meals into smaller chunks throughout the day, but if it persists, it is wise to contact a veterinarian.
Dr. Karen Becker on Healthy Pets cautions pet owners against believing the myth that vomiting is natural for cats; vomiting is always a sign that something is wrong, even if the problem is relatively minor. Cats usually vomit early in the morning or late at night, shortly before being fed. An easy way to prevent bilious vomiting is to maintain a consistent meal schedule or supplement the cat's diet with small treats.
AssistFeed recommends mixing dry food with some water to create a broth for the cat early in the morning to help settle its stomach before breakfast and prevent any further occurrences. If smaller, more frequent meals fails to fix the problem, a vet may be able to recommend a medication to help settle its stomach. A stuck hairball also sometimes cause foamy white vomit and can be prevented by brushing the cat regularly and increasing fiber in its diet.