Answer: The surface of the cat’s tongue is covered with numerous horny projections, the filifrom papillae. These are arranged to point backwards, i.e. towards the back of the throat. It is these papillae which give the characteristic rough feel to the cat’s tongue. Because of them, the tongue can be used as rasp to remove flesh from bones, and they are also important in grooming, enabling the cat to remove loose hairs from its coat.
The presence of the papillae also account for the tendency of cats to swallow needles. A playful cat may be attracted by the thread attached to a needle and having begun to play with the thread, then finds that it becomes entangled in the papillae. The thread cannot be moved forwards because the papillae point backwards. But by gulping, it is possible for the cat to move the thread backwards. So gradually the thread is taken further and further into the mouth, drawing the needle with it. Eventually thread and needle can only be freed from the tongue by being swallowed. The needle may penetrate the wall of the throat, or somewhere further down the digestive tract, but it is usually swallowed blunt end first. Quite often a cat is lucky and the needle passes right though the digestive tract without causing problems.
There are also other types of papillae (vallate and fungiform) on certain areas of the tongue. These contain the test buds able to detect different types of taste, although sweet tastes cannot be discerned by the cat.
