When I took my Trevor to the vet for the first time as a wee little kitten I of course had to take a stool specimen. When he came back into the exam room he told me "the good news is his stool tests negative for everything except string." He then gave this first time cat owner an education on the horrors of cats eating string, much as Sallyanne just did. I would encourage everyone here to be careful of string and when Christmas comes around tinsel is another problem.