Australian poet Pam Brown once wrote, "Cats can work out mathematically the exact place to sit that will cause the most inconvenience." They seem to have the same knack for vomiting–as virtually every cat owner has experienced a hairball in the shoe, 'snarf and barf' on the landing, or melodious retching on the bed in the wee hours of the morning. Why have cats–some of them at least–made vomiting a part of their daily lives? While heaving can sometimes be a sign of serious illness, most vomiting is relatively harmless. Consider these common causes of cat retching and what to do about them.