Croup is one of those things that young children seem to get often in novels, and no doubt in real life as well. It generally occurs in kids between the ages of three and six, and its most common symptoms are a high-pitched cough and difficulty in breathing. Medically, croup is known as acute obstructive laryngitis, and its causes are myriad: a bacterial infection like flu or diptheria; an allergy; a swallowed object; or even, at the scariest extreme, a tumor of the larynx. Treatment depends on cause: antibiotics for a bacterial infection; epinephrine or similar drugs for an allergy; removal of the blockage. Steam inhalation from a vaporizer or hot-water faucet can often relieve breathing difficulties, but in severe cases oxygen may be required, or the cutting of an opening in the trachea to prevent suffocation. I hope none of you ever have to do this to any child you know, and that, if you do, your first aid skills are up-to-date.