When a chicken eats a small, sharp object such as a tack or staple, the object is likely to get stuck in the gizzard. Because of the strong grinding motion of the giz- zard’s muscles, these sharp objects may eventually put a hole in the gizzard wall. Chickens with dam- aged gizzards will grow thin and eventually die – a very good reason to keep your poultry houses free of nails, glass shards, bits of wire and the like.