Croup is one of the most common respiratory illnesses in children. It is an inflammation of the larynx and the trachea. When a child has croup, that portion of the airway just below the vocal cords narrows and becomes swollen, making breathing both noisy and labored.
Croup is a broad term describing a group of illnesses that affect the larynx, trachea, and bronchi. The key symptom is a harsh, barking cough . One of the most common respiratory illnesses in children, croup is frequently noted in infants and children and can have a variety of causes. Before the days of antibiotics and immunizations, croup was a dreaded and often deadly disease usually caused by the diphtheria bacteria. Though in the early 2000s cases of croup are normally mild, it can still be dangerous. Croup affects the vocal cords and the area just below, the voice box, or larynx, and the windpipe, or trachea. The lower breathing passages (bronchi) may also be affected. Swelling of these areas causes the airway to narrow, which makes breathing difficult. It is also sometimes called laryngotracheitis, a medical term describing the inflammation of the trachea and larynx.
The characteristic symptoms of croup can be better understood by knowing the anatomic makeup of a child's larynx. Small children typically have quite a narrow larynx, so even a slight decrease in the airway's radius may lead to a large decrease in the air flow, leading to the symptoms of croup.
There are two primary types of croup: viral and spasmodic. Viral croup is caused by a viral infection in the trachea and larynx. It often starts with a cold that over time develops into a barking cough. When the child's airway becomes increasingly swollen and more mucus is secreted, it becomes more challenging to breathe. Breathing gets increasingly noisy, and a condition known as stridor may occur. (Stridor is a sign of respiratory obstruction that presents as a high-pitched, coarse, musical sound that occurs during breathing.) Children with viral croup usually have a low-grade temperature, but a few may have fevers up to 104°F (40°C). As breathing requires more effort, the child may stop eating and drinking. The child may also become too fatigued to even cough. If the airway continues to swell, it may approach a point at which the child can no longer breathe. Stridor is fairly common with a mild case of croup, especially if the child is active or crying. However, if a child has stridor at rest, the child may have severe croup. Symptoms are usually worse at night. The symptoms peak between 24 and 48 hours and usually resolve within one week.
Spasmodic croup is usually precipitated by an allergy or mild upper respiratory infection. It can be quite alarming, both because of the noise of the cough and because it usually comes on suddenly in the middle of the night. A child may go to sleep with a mild cold and wake up a few hours later, gasping for air. In addition, the child may have a cough that sounds like a seal barking, and will have a hoarse voice. Children with spasmodic croup normally do not have a fever .
Spasmodic croup can sometimes be difficult to differentiate from viral croup. Although spasmodic croup is associated with the same viruses that cause viral croup, spasmodic croup tends to recur and may be an indication of some type of allergic reaction instead of a direct infection.
The viruses causing croup are highly contagious and easily transmitted between individuals through sneezing and coughing. It is usually transmitted via the respiratory route, entering through the nose and nasopharynx.
Croup accounts for about 15 percent of all respiratory tract infections in children seen by physicians. It typically is seen in late fall and winter, and primarily occurs in children aged six months to three years. It has an annual peak incidence of 50 new cases per 1,000 children during the second year of life. Males are twice as likely as females to get the disease. The incidence decreases significantly after age six.
Causes and symptoms
Croup is most commonly brought on by a viral infection. The parainfluenza viruses (types 1, 2, and 3) are the most frequent causes of croup, accounting for approximately 75 percent of all cases diagnosed. Human parainfluenza virus 1 (HPIV-1) is the most common cause. Croup may also be caused by influenza A and B, adenovirus, measles , and respiratory syncytial virus (RSV). Other possible causes of croup are bacteria, inhaled irritants, allergies , and acid reflux.
The following are usually true of viral croup:
- It commonly occurs in individuals between the ages six months to six years.
- Stridor, and the classic barking cough are usually present.
- The child may have a fever.
- Wheezing may be present.
- It usually lasts two to seven days.
The following items are characteristic of spasmodic croup:
- The symptoms come on suddenly, often in the middle of the night.
- Stridor occurs along with the barking cough.
- It typically lasts two to four hours.
When to call the doctor
Most cases of croup can be safely managed at home, but parents should call their child's doctor for advice, even if it is in the middle of the night. Call 911 for emergency help if any of the following is true:
- The croup is possibly caused by an inhaled object or by an insect sting.
- The child is drooling.
- The child has blue lips or skin.
- The child has a very high fever.
- The child is very anxious, has rapid breathing, and/or is struggling to get a breath.
- The child insists on sitting up or complains of a sore throat and is drooling. This is a possible indication that he or she may have a disease called epiglottitis , which is potentially life-threatening.
- The child makes a whistling sound that gets louder with each breath.
- The child has stridor when resting.
The diagnosis of croup is usually made based on the description of symptoms by the parent, as well as a physical examination. Sometimes other studies, such as x rays , may be required. The doctor may note chest retractions with breathing and may hear wheezing and decreased breath sounds when listening to the chest with a stethoscope. Sometimes a foreign object or narrowing of the trachea is seen on a neck x ray.
The most important part of treating patients with croup is maintaining an open airway. If a child wakes up in the middle of the night with croup, he or she should be taken to the bathroom. The door should be closed and the shower turned on to allow the bathroom to steam up. The parent should then sit in the steamy bathroom with the child. The moist, warm air should assist the child in breathing within 15 to 20 minutes, though the child will still have the barking cough. For the rest of that night and for two to three nights following, a humidifier or cold-water vaporizer should be placed in the child's room. If another attack of croup recurs that night or the next, the steam treatment should be repeated. If the steam does not work, sometimes taking the child outside, where he or she can inhale the cool, moist night air will be enough to improve breathing. Though a study in the early 2000s cast some doubt on the efficacy of using steam or mist, it does seem to be helpful for most children with croup. Parents may also give acetaminophen to reduce fevers and increase the child's comfort level. Cough medicines should usually be avoided.
Several other treatments are possible if the croup is severe enough to warrant the child's being seen by a physician. Aerosolized racemic epinephrine as well as oral dexamethasone (a steroid) may be used to help shrink the upper airway swelling. A bacterial infection will require antibiotics. If the airway becomes increasingly obstructed, the child may require intubation (the placing of a tube through the nose or mouth through the larynx into the main air passage to the lungs.) If the patient is dehydrated, intravenous fluids will be administered.
Croup is normally a self-limiting disease with an excellent prognosis. Only a few who are diagnosed require hospitalization , and less than 5 percent require intubation. If proper airway management is maintained, death is rare. There is some speculation that children with a history of croup may be at a higher risk for developing asthma , but the evidence was not clear as of 2004.
The best way to prevent croup is to prevent the causative infections. Parents should practice excellent hand washing, especially during the cold and flu season, and avoid close contact with anyone who has a respiratory infection.
The onset of croup can be frightening, especially when it comes on suddenly. Parents can help their child by not panicking or appearing anxious, as this may increase anxiety in the child, which can worsen symptoms. If they are at all unsure about how their child is responding to home treatment, parents should not hesitate to seek medical advice or treatment, no matter the time of day or night.
See also Influenza.
Colletti, James E. "Myth: Cool Mist Is an Effective Therapy in the Management of Croup." Canadian Journal of Emergency Medicine 6 (September 2004): 5, 357–9.
Knutson, Doug, and Ann Aring. "Viral Croup." American Family Physician 69 (February 1, 2004): 3, 535–40.
"Patient Education Guide: What to Do When Your Child Has Croup." Journal of Respiratory Diseases 23 (March 2002): 23, 192–5.
American Academy of Pediatrics. 141 Northwest Point Boulevard, Elk Grove Village, IL 60007–1098. Web site: <www.aap.org>.
"Croup." MedlinePlus. Available online at <www.nlm.nih.gov/medlineplus/ency/article/000959.htm> (accessed January 11, 2005).
Deanna M. Swartout-Corbeil, RN
Epiglottitis —Inflammation of the epiglottis, most often caused by a bacterial infection. The epiglottis is a piece of cartilage behind the tongue that closes the opening to the windpipe when a person swallows. An inflamed epiglottis can swell and close off the windpipe, thus causing the patient to suffocate. Also called supraglottitis.
Larynx —Also known as the voice box, the larynx is the part of the airway that lies between the pharynx and the trachea. It is composed of cartilage that contains the apparatus for voice production–the vocal cords and the muscles and ligaments that move the cords.
Retractions —Tugging-in between the ribs when breathing in.
Stridor —A term used to describe noisy breathing in general and to refer specifically to a high-pitched crowing sound associated with croup, respiratory infection, and airway obstruction.
Trachea —The windpipe. A tube composed of cartilage and membrane that extends from below the voice box into the chest where it splits into two branches, the bronchi, that lead to each lung.
Croup is a common childhood ailment. Typically, it arises from a viral infection of the larynx (voice box) and is associated with mild upper respiratory symptoms such as a runny nose and cough. The key symptom is a harsh barking cough. Croup is usually not serious and most children recover within a few days. In a small percentage of cases, a child develops breathing difficulties and may need medical attention.
At one time, the term croup was primarily associated with diphtheria, a life-threatening respiratory infection. Owing to widespread vaccinations, diphtheria has become rare in the United States, and croup currently refers to a mild viral infection of the larynx. Croup is also known as laryngotracheitis, a medical term that describes the inflammation of the trachea (windpipe) and larynx.
Parainfluenza viruses are the typical root cause of the infection, but influenza (flu) and cold viruses may sometimes be responsible. All of these viruses are highly contagious and easily transmitted between individuals via sneezing and coughing. Children between the ages of three months and six years are usually affected, with the greatest incidence at one to two years of age. Croup can occur at any time of the year, but it is most typical during early autumn and winter. The characteristic harsh barking of a croupy cough can be very distressing, but it rarely indicates a serious problem. Most children with croup can be treated very effectively at home; however, 1-5% may require medical treatment.
Croup may sometimes be confused with more serious conditions, such as epiglottitis or bacterial tracheitis. These ailments arise from bacterial infection and must receive medical treatment.
Causes and symptoms
The larynx and trachea may become inflamed or swollen from an upper respiratory viral infection. The hallmark sign of croup is a harsh, barking cough. This cough may be preceded by one to three days of symptoms that resemble a slight cold. A croupy cough is often accompanied by a runny nose, hoarseness, and a low fever. When the child inhales, there may be a raspy or high-pitched noise, called stridor, owing to the narrowed airway and accumulated mucus. In the presence of stridor, medical attention is required.
However, the airway rarely narrows so much that breathing is impeded. Symptoms usually go away completely within a few days. Medical treatment may be sought if the child's symptoms do not respond to home treatment.
Emergency medical treatment is required immediately if the child has difficulty breathing, swallowing, or talking; develops a high fever (103°F/39.4°C or more); seems unalert or confused; or has pale or blue-tinged skin.
Croup is diagnosed based on the symptoms. If symptoms are particularly severe, or do not respond to treatment, an x ray of the throat area is done to assess the possibility of epiglottitis or other blockage of the airway.
Home treatment is the usual method of managing croup symptoms. It is important that the child is kept comfortable and calm to the best degree possible, because crying can make symptoms seem worse. Humid air can help a child with croup feel more comfortable. Recommended methods include sitting in a steamy bathroom with the hot water running or using a cool-water vaporizer or humidifier. However, research in 2004 found that although cool-mist therapy at home or in the hospital may add to the child's comfort, it does little to treat the actual condition. The child should drink frequently in order to stay well hydrated. To treat any fever, the child may be given an appropriate dose of acetaminophen (like Tylenol). Antihistamines and decongestants are ineffective in treating croup. All children under the age of 18 should not be given aspirin, as it may cause Reye's syndrome, a life-threatening disease of the brain.
If the child does not respond to home treatment, medical treatment at a doctor's office or an emergency room could be necessary. Based on the severity of symptoms and the response to treatment, the child may need to be admitted to a hospital.
For immediate symptom relief, epinephrine may be administered as an inhaled aerosol. Effects last for up to two hours, but there is a possibility that symptoms may return. For that reason, the child is kept under supervision for three or more hours. Steroids (corticosteroids ) such as prednisone may be used to treat croup, particularly if the child has stridor when resting.
Of the 1-5% of children requiring medical treatment, approximately 1% need respiratory support. Such support involves intubation (inserting a tube into the trachea) and oxygen administration.
Botanical/herbal medicines can be helpful in healing the cough that is commonly associated with croup. Several herbs to consider for cough treatment include aniseed (Pimpinella anisum ), sundew (Drosera rotundifolia ), thyme (Thymus vulgaris ), and wild cherry bark (Prunus serotina ). Homeopathic medicine can be very effective in treating cases of croup. Choosing the correct remedy (a common choice is aconite or monkshood, Aconitum napellus ) is always the key to the success of this type of treatment.
Croup is a temporary condition and children typically recover completely within three to six days. Children can experience one or more episodes of croup during early childhood; however, croup is rarely a dangerous condition.
Croup is caused by highly transmissible viruses and is often difficult to impossible to prevent.
Kirn, Timothy F. "Cool Mist Therapy is Losing Credibility for Croup: Steroids or Even Epinephrine May Be Needed." Pediatric News March 2004: 10-11.
Diphtheria— A serious, frequently fatal, bacterial infection that affects the respiratory tract. Vaccinations given in childhood have made diphtheria very rare in the United States.
Epiglottitis— A bacterial infection that affects the epiglottis. The epiglottis is a flap of tissue that prevents food and fluid from entering the trachea. The infection causes it to become swollen, potentially blocking the airway. Other symptoms include a high fever, nonbarking cough, muffled voice, and an inability to swallow properly (possibly indicated by drooling).
Glucocorticoid— A hormone that helps in digestion of carbohydrates and reduces inflammation.
Larynx— Commonly called the voice box, it is the area of the trachea that contains the vocal cords.
Stridor— The medical term used to describe the high-pitched or rasping noise made when air is inhaled.
Trachea— Commonly called the windpipe, it is the air pathway that connects the nose and mouth to the lungs.
Croup is a common ailment of early childhood involving inflammation of the larynx, trachea, bronchial tubes, and lungs. The condition is characterized by a harsh, barking cough, wheezing , and difficulty in breathing.
Croup is most likely to be found in children between the ages of three months to six years. Most incidences occur during the cold weather seasons.
Spasmodic croup is usually mild and may be due to bacterial infection or allergies . For the most part, the child will not have a fever . Viral croup, also called laryn-gotracheobronchitis, is more severe and is often accompanied by fever. Both types follow a very similar course, which depends on the severity of the illness.
In many instances, a child may have had a cold or the flu just before the onset of croup symptoms. These symptoms tend to come on very suddenly. It is not uncommon for a child with croup to waken in the middle of the night coughing violently and gasping for breath. In fact, the croup symptoms will usually be worse at night and get better during the day.
Causes & symptoms
During the immune system response to an infection or an allergic reaction, the respiratory passages become swollen, and they are congested with mucus and fluid. They also become more and more irritated. There is a great deal of coughing, and the child may become hoarse. The airways are narrowed, and the breathing is difficult and noisy. This leads to the characteristic symptom of stridor, or noisy aspiration, as the child attempts to draw in air through narrowed passages. The constriction of these airways is usually accompanied by a high-pitched cough, often described as sounding like the bark of a seal.
Diagnosis of croup is primarily based on a good history taken by the health care provider, including the physical symptoms of the illness, the presentation of the illness, and its progression. If a physical exam is performed, it will probably include listening with a stethoscope for the breathing sounds which are characteristic of croup. When the symptoms appear to be severe, or the history suggests it, x rays may be taken to rule out epiglottitis (infection of the epiglottis) or aspiration of a foreign body, which are emergency situations.
Most treatment can be done at home, using relaxing and supportive measures to relieve symptoms. Steam inhalation is quite helpful in this respect. A cool-mist humidifier is recommended, as a hot vaporizer is often hazardous, especially around young children.
One of the best ways to produce a lot of moist air in a short time, is to make use of the bathroom shower. The procedure is to close the bathroom door and turn on the cool water shower faucet full blast. Then the child can be a held while seated on a chair or the closed commode, breathing in steam as it fills the room. This can be done for up to 15 minutes, and often brings instant relief from congestion.
Cool air seems to relax and soothe the respiratory system. Therefore, taking a car ride with the window rolled will sometimes effect good results in reducing the coughing associated with croup.
There is a strong possibility of dehydration due to the illness. Increasing fluid intake as much as possible and insuring plenty of rest will enhance immune functioning, helping the body to help itself. In addition, smoking should be prohibited within the house.
Respiratory herbs can be used to soothe swollen and irritated tissues, reduce inflammation, and gently loosen and expel mucus. The following herbs should be given three times per day diluted in water or other liquids until symptoms are gone:
- Grindelia spp., gum weed, 1-2 ml
- Sambucus nigra, elder flowers, 2-4 ml
- Glycyrrhiza glabra, licorice root, 1-3 ml
- Verbascum thapsus, mullein , 2-4ml
- Astragalus senticocosus, 2-4 ml (This herb is an immune system stimulant and should be given as a preventative for those who have chronic bouts of croup.)
Slippery elm bark can also be taken, as it is soothing to the throat.
Aconite is the most favored remedy to use for croup. If it does not work, Spongia can be tried, especially if the breathing sounds as if wood were being sawed. Alternately, try Hepar sulphuris, indicated by a mucus-filled cough. Give a dosage of 12X or 30C every 30 minutes until the child is able to fall asleep.
In most cases, croup can be easily and successfully treated at home. However, if the symptoms become severe, the child will need to be seen by a physician. Prompt medical attention is needed if:
- The child's fever goes up to 104°F (39.9°C).
- The child seems pale or bluish around the mouth or fingernails.
- The child refuses all liquids or can't swallow.
- The child is drooling a great deal.
- The child's breathing becomes increasingly rapid or difficult.
Severe cases may warrant the use of inhalants, such as epinephrine, to reduce swelling and give the child easier breathing. Inhalants have limited effectiveness over time, and care must be taken to avoid undesirable side effects. Oxygen may also be administered in more severe cases. Corticosteroids are given to decrease pain and swelling.
If a child is hospitalized for further observation or treatment, intravenous (IV) fluids may be given to reduce dehydration. In a few very severe cases, a tube has to be inserted through the nose or mouth (intubation) to keep the airway passage open for breathing. There is a slight risk of injury to the respiratory system during the introduction and the removal of the tube.
Croup ordinarily lasts three to seven days. Most cases are mild and gradually improve with care. Some children have recurring bouts with croup, but they usually outgrow this by seven years of age.
It is important to monitor a child with croup throughout the night. An adult should probably consider sleeping or resting nearby. If the child is having a serious struggle with breathing, emergency services should be contacted immediately. This means either calling 911 or making a trip to the nearest emergency room. Hospital visits are necessary in about one to 15% of the reported cases of croup.
Croup is generally the result of an infectious disease. Avoiding exposure to others with respiratory infections is the best way to avoid getting croup. Children should be taught to maintain good hygiene practices such as not eating food from the silverware or dishes of others and washing their hands. Care should be taken with colds and the flu so that there is no progression to symptoms of croup.
In general, an adequate intake of vitamins A and C, bioflavonoids , and zinc can help to prevent the respiratory infections and allergic reactions that lead to croup.
The Editors of Time-Life Books. The Medical Advisor: The Complete Guide to Alternative and Conventional Treatments. Alexandria, VA: Time-Life, Inc., 1997.
"Childhood Infections" The Nemours Foundation. http://kidshealth.org. (1999).
"The Common Cold" Natural Medicine Online. http://www.nat-med.com. (2000).
"Croup" Merck & Co., Inc. http://www.merck.com.
"Croup and Your Young Child" American Academy of Pediatrics. http://www.aap.org. (2000).
Croup (KROOP) is an infection involving the trachea (windpipe) and larynx (voice box) that typically occurs in childhood. It causes inflammation and narrowing of the upper airway, sometimes making it difficult to breathe. The characteristic symptom is a barking cough.
Croup is an infection of the throat typically occurring in childhood that causes the lining of the trachea* and larynx* to swell, narrowing the upper airway and sometimes making it difficult to breathe. The characteristic symptom is a barking cough. In more severe cases of croup, a high-pitched or squeaking noise called stridor* can be heard when the child takes a breath. The symptoms of the infection can appear suddenly, or develop over a few days. Common cold symptoms, such as a runny nose, usually precede the onset of the barking cough. An allergy or a bacterial infection can produce symptoms of croup, but the most common culprit is a virus, usually parainfluenza* virus. Influenza viruses, adenovirus*, respiratory syncytial virus*, and measles virus also can cause croup.
- (TRAY-kee-uh) is the windpipe, the firm, tubular structure that carries air from the throat to the lungs.
- (LAIR-inks) is the voice box (which contains the vocal cords) and is located between the base of the tongue and the top of the windpipe.
- (STRY-dor) is a high-pitched, squeaking noise that occurs while breathing in, present usually only if there is narrowing or blockage of the upper airway.
- (pair-uh-in-floo-EN-zuh) is a family of viruses that cause respiratory infections.
- (ah-deh-no-VY-rus) is a type of virus that can produce a variety of symptoms, including upper respiratory disease, when it infects humans.
- *respiratory syncytial
- (RES-puh-ruh-tor-e sin-SIH-she-ul) virus , or RSV, is a virus that infects the respiratory tract and typically causes minor symptoms in adults but can lead to more serious respiratory illnesses in children.
Croup is most common during the winter months and in the early spring. The condition tends to develop in children who are between the ages of 3 months and 5 years. In the same way that an adult with a cold might have laryngitis*, a child with a cold might get croup. In fact, many of the viruses that cause croup in children can lead to laryngitis in adults. Some children are more prone to croup, such as those who are born prematurely or who have narrowed upper airways. These children may get symptoms of croup every time they have a respiratory illness. Although the viruses that cause croup can pass easily between children through respiratory secretions, most children who come into contact with those viruses will not get croup.
- (lair-in-JY-tis) is an inflammation of the vocal cords that causes hoarseness or a temporary loss of voice.
A low fever is common, and children with croup usually have a barking cough. In severe cases, when their airways become more swollen and narrowed, children might experience difficulty breathing. Fast breathing and stridor may develop. If the body is not getting enough oxygen, the lips, tongue, and skin around the mouth can start to appear bluish. Crying can make the breathing symptoms worse. The symptoms also tend to worsen at night, when children are tired, and a child with croup often will have trouble sleeping or even resting. Croup symptoms typically peak 2 to 3 days after they start, and the illness generally lasts less than a week. In a small number of cases, children may have such complications as an ear infection or pneumonia.
A barking cough and stridor are telltale signs of croup. Other clues to the diagnosis are low fever, common cold symptoms, previous bouts of croup, or a history of intubation* or other upper-airway problems. If the symptoms are severe, or if the child does not respond quickly to treatment, a neck X ray may be taken to check for other reasons for the breathing difficulty. The X ray might show a foreign object lodged in the throat or, possibly, epiglottitis*. If the air passage at the top of the trachea is narrowed almost to a point (called a “steeple sign”), it helps confirm the diagnosis of croup.
- (in-too-BAY-shun) is the insertion of a tube into the windpipe to allow air and gases to flow into and out of the lungs in a person who needs help breathing.
- (eh-pih-glah-TIE-tis) is a condition involving life-threatening swelling of the epiglottis (a soft flap of tissue that covers the opening of the trachea when a person swallows), which is usually caused by a bacterial infection of the epiglottis. The condition can result in a blockage of the trachea and severe breathing difficulty.
Mild cases of croup can be treated safely at home. Moist air is especially helpful, and mist from a steam-filled bathroom or cool-mist humidifier will moisten the child’s airway, help open the air passage, and relieve coughing. Taking the child outdoors for a few minutes, even in the winter, can ease a coughing attack quickly, because the cool air can shrink the swollen tissues lining the airway. As with most illnesses, drinking fluids and getting plenty of rest help the body heal. Cigarette smoke near a child with croup or any other respiratory illness can make symptoms worse. Doctors advise prompt medical treatment for serious croup infections. Inhaled medications, including epinephrine*, can minimize swelling in the upper airways. Doctors often will administer corticosteroid* medicines to ease airway swelling for a few days while the child recovers from the virus infection that causes croup. There is no way to prevent croup, but frequent hand washing and avoiding contact with people who have respiratory infections can lessen the chance of spreading the viruses that cause croup.
- (eh-pih-NEH-frin) is a chemical substance produced by the body that can also be given as a medication to constrict, or narrow, small blood vessels, stimulate the heart, and cause other effects, such as helping to open narrowed airways in conditions like asthma and croup.
- (kor-tih-ko-STIR-oyds) are chemical substances made by the adrenal glands that have several functions in the body, including maintaining blood pressure during stress and controlling inflammation. They can also be given to people as medication to treat certain illnesses.
Telephone 800-311-3435 http://www.cdc.gov
KidsHealth.org. KidsHealth is a website created by the medical experts of the Nemours Foundation and is devoted to issues of children’s health. It contains articles on a variety of health topics, including croup.
croup1 / kroōp/ • n. inflammation of the larynx and trachea in children, causing breathing difficulties.DERIVATIVES: croup·y adj.croup2 • n. the rump or hindquarters, esp. of a horse.