String is irresistible to cats, and almost every cat loves to play with string in all of its forms: yarn, ribbon, shoelaces and even dental floss. Strings are fun for cats to chase, bat and pounce upon, and it often ends up in the mouth. Even though a brightly-colored ribbon is an inexpensive toy for your cat, it can actually result in an expensive medical emergency for your cat.

Cats don’t intentionally swallow string; their unique tongues are to blame for much of the problem. You’ve probably noticed that a cat’s tongue feels like sandpaper. This is because a cat’s tongue is covered with backward-facing barbs called papillae. These barbs help a cat to rasp meat from the bones of their prey, and are also a great grooming tool. Unfortunately, the backward-facing barbs make it difficult for your cat to spit out a piece of string once it has gotten into the mouth.

A swallowed string, or “linear foreign body,” can be a medical emergency that sometimes requires surgical intervention. Although string may pass through your cat’s digestive tract uneventfully, a swallowed string can lead to intestinal obstruction or perforation. A piece of string can also get looped beneath your cat’s tongue, causing injury to the tongue. If you suspect your cat has swallowed a piece of string, contact your vet for medical advice. Never pull on a piece of string you see protruding from your cat’s mouth or bottom, as you may cause serious injury to your cat.

Prevention is key in this case: don’t leave strings such as thread or dental floss out where your cat can get to it, and most experts recommend that you avoid using Christmas tinsel and Easter grass. Never allow your cat to play with a string-like object unsupervised, and put the toy away when you’re done playing.

Cats are curious and playful, and love toys. You can indulge your cat’s love of play, but just choose cat toys wisely.