If the bowel becomes obstructed by tinsel, most commonly it has to be corrected through surgery by removing the blockage from the intestines. If the tinsel becomes lodged in the stomach, occasionally we are able to remove it without surgery using an endoscope, but not every veterinary clinic has suitable equipment.
Long pieces of tinsel can become partially lodged under the tongue or in the stomach. Unfortunately, only one end is lodged, and the rest of the tinsel can be stretched and moved inside the intestines creating a cheese-wire like damage. When multiple areas of the intestines are damaged, the surgery becomes much more difficult and, in some cases, the patient can die due to complications.
If your cat ingests tinsel, depending on circumstances, your vet may elect to try to make him sick to retrieve the tinsel, monitor it (as many pieces can pass on their own), or suggest surgery if there are any signs that indicate the internal problem.