Why is it bad to leave hay bale strings in a horse's hay?

Question

I was working at the barn I take lessons at and I left one haystring in a horse's hay. My trainer, therefore, has asked me to look up why leaving haystrings is bad. I can't find anything on the Internet, so here I am on Yahoo! Answers. If you guys have any internet articles for sources, that'd be great because then I can read more in depth into the subject.

Answer 1

 In my situation...yesterday my horse was rushed to the surgery.... After 4 hours of surgery, the vet found that he ingested bailing twine. He exact words...."a massive amount of bailing twine!"  I will never ever forget those words.  When the vet called a 1:30 in the morning saying he is almost inoperable we will work on him for the next half an hour but prepare yourself to put him down on the table.  Devastated is all I can say.  This beautiful strong race horse, fit and otherwise healthy, 4 weeks off racing -  we are hoping we got him in time.  He is still in a critical state but his colon is severely damaged.  Your trainer is right in getting you to check...I checked the feeder but extra bits used such as tie ups need to be monitored as well!  Please pray for our beautiful Duke.....