The upper respiratory system is made up of the nasal passages, throat, larynx and trachea. The bronchi and lungs make up the lower respiratory tract. The breathing tubes branch into progressively smaller passages until they open into the air sacs (alveoli). The lungs are composed of the bronchi, air sacs, and blood vessels. The ribs and muscles of the chest, along with the diaphram, function as a bellows, moving the air into and out of the lungs.

Abnormal Breathing

Rapid, Labored Breathing

A dog at rest takes about 10 to 30 breaths per minute. 

Breathing at a faster rate suggests fever, pain, anxiety or a problem with the lungs or chest. Rapid breathing should be distinguished from panting. Panting is the primary way a dog lowers his body temperature; water evaporates from the mouth, tongue, and lungs and warm air in the body is exchanged for cooler air in the atmosphere. Rapid breathing, when accompanied by labored or difficult breathing, is a sign of distress. Dogs with congestive heart failure and/or lung disease often have rapid labored breathing at rest or with only mild exertion. Other causes of rapid, labored breathing

are shock, heat stroke, dehydration and ketoacidosis associated with diabetes, kidney failure and some kinds of poisoning. Dogs with rapid, labored breathing should be seen by a trained professional.

Noisy Breathing

Noisy breathing indicates an obstruction in the nasal passages, the back of the throat or the larynx. Snorting and snoring are typically heard with the brachycephalic syndrome. If your dog normally breathes quietly but suddenly develops noisy breathing, this is a cause for concern. He should be checked by a trained professional.

Stridor (Croupy Breathing)

Croupy breathing or stridor, is a high-pitched raspy sound caused by air passing through a narrowed voice box. It may be heard only when the dog exercises. When the onset is sudden, the most likely cause is a foreign body in the voice box. When croupy breathing has been present for some time, laryngeal paralysis is a possible cause.

Wheezing

A wheeze is a whistling sound heard when the dog inhales or exhales, or both. Wheezing indicates spasm or narrowing in the trachea or bronchi. Wheezes in the lungs are best heard with a stethoscope. Some causes of wheezing are chronic bronchitis, congestive heart failure, and tumors of the larynx, trachea, and lungs.

Shallow Breathing

Shallow breathing is seen in dogs with broken ribs and severe bruising of the chest wall. Blood, pus or serum in the chest cavity (called pleural effusion) restricts breathing by interfering with the range of motion of the chest and expansion of the lungs. A dog with shallow breathing compensates by breathing more rapidly.

Brachycephalic Syndrome

Bulldogs, Pugs, Pekingese, Shih Tzu, English Toy Spaniels, Boston Terriers, Chow Chows and other dogs with broad skulls and short muzzles frequently show some degree of airway obstruction, known as brachycephalic  syndrome, manifested by mouth breathing, snorting and snoring. These difficulties become more pronounced when the dog is exercising or is overheated and tend to get worse as the dog grows older. The obstructed breathing in these dogs is caused by deformities that include collapsed nostrils, an elongated soft palate and eversion of the laryngeal saccules. These deformities often occur together. Collapsed nostrils and elongated soft palate are congenital. Eversion of the laryngeal saccules is acquired.

Stenotic Nares (Collapsed Nostrils)

In puppies with stenotic nares, the nasal openings are small and the nasal cartilage is soft and floppy, causing the nostrils to collapse as the puppy breathes in. This produces varying degrees of airway obstruction, manifested by mouth breathing, noisy breathing and occasionally a nasal discharge. In severe cases the chest is flattened from front to back. These pups fail to thrive and are poorly developed.

Elongated Soft Palate

The soft palate is a flap of mucosa that closes off the nasopharynx during swallowing. Normally, it touches or slightly overlaps the epiglottis. In dogs with an elongated soft palate, the palate overlaps the epiglottis to a considerable degree, partially obstructing the airway during breathing. This is manifested by snorting, snoring, stridor, gurgling and gagging. The obstruction is worse with exercise. In time, stretched ligaments in the larynx lead to labored breathing and laryngeal collapse.

Eversion of the Laryngeal Saccules

Laryngeal saccules are small mucosal pouches that project into the larynx. In long-standing upper airway obstruction the saccules enlarge and turn out (eversion), narrowing the airway even further.  

The Larynx (Voice Box)

The larynx is an oblong box of tissue located in the throat above the windpipe (trachea). Just above the larynx and protects the epiglottis, a leaflike flap of cartilage that closes over the larynx and protects the airway during swallowing. The larynx is composed of cartilage held together by ligaments. Within the larynx are the vocal cords, which is why the larynx is sometimes called the voice box. A dog's vocal cords are thick and prominent, enabling them to bark loudly. The interior of the larynx is lined with a mucous membrane. The mucosa of the larynx, unlike the rest of the respiratory tract, does not contain cilia-hairlike structures that help move things through the passage. Therefore, mucus tends to pool in the larynx. Exaggerated throat-clearing is required to bring up the phlegm. The larynx is the most sensitive cough area in the respiratory tract. Pressure over the larynx, such as that caused by a tight choke collar, can cause episodes of explosive coughing. Diseases of the larynx cause hoarseness and progressive loss of the ability to bark. Choking, gagging and coughing may be observed, especially while eating or drinking. Laryngeal obstructions such as those caused by laryngeal collapse, vocal cord paralysis or a foreign body in the airway produce shortness of breath on exertion, stridor, cyanosis and collapse.

Laryngitis

Laryngitis is inflammation and swelling of the vocal cords and surrounding laryngeal mucosa. The signs are hoarseness and the inability to bark. The most common cause of laryngitis is voice strain caused by excessive barking or coughing. In the absence of these, suspect vocal cord paralysis. Laryngitis can accompany tonsillitis, throat infections, kennel cough or tumors in the throat.

Laryngeal Edema

Sudden swelling of the larynx and vocal cords can result in marked narrowing or complete obstruction of the airway. Signs are stridor, rapid labored breathing, cyanosis and collapse. Insect bites can cause an anaphylactic reaction with sudden swelling of the larynx. Another cause of laryngeal edema is excessive panting, particularly when it is associated with heat stroke. Similarly, any process that results in forced breathing across a narrowed airway (such as vocal cord paralysis) can lead to swelling that exacerbates the original disease.

Choking (Foreign Body in the Larynx)

The sudden onset of forceful coughing, pawing at the mouth and respiratory distress in a healthy dog suggests a foreign body caught in the larynx. This is an emergency! If the dog is conscious and able to breathe, proceed at once to the nearest animal hospital or clinic. If your dog is gagging and retching but is not experiencing difficulty in breathing, assume a foreign object such as a bone splinter or rubber ball is caught in his mouth or in the back of his throat. Fortunately, a foreign body in the larynx is not common. Most objects are expelled by the forceful coughing that results from laryngeal stimulation.

The Heimlich Maneuver

1. Abdominal compressions:  It may be easiest to hold the dog upside down in your lap, with her back against your chest and his head highest, but facing down. place your arms around the dog's waist from behind. Make a fist and grasp it with the other hand. For a small dog, you may have to just use two fingers. Place your fist or fingers in the dog's upper mid-abdomen close to the breast bone at the apex of the V formed by the rib cage. Compress the abdomen by forcefully thrusting up and in with the fist or fingers four times in quick succession. This maneuver pushes the diaphragm upward and forces a burst of air through the larynx. This usually dislodges the object.

2. Finger sweeps: Pull out the tongue and sweep the mouth. Remove the foreign body and proceed to step 5. If you are unable to dislodge the object proceed to step 3.

3. Artificial respiration: Give five mouth-to-nose respirations. Even a small volume of air getting past the obstruction is beneficial. Proceed to step 4.

4. Chest thumps: Deliver a sharp blow with the heel of your hand to the dog's back between the shoulder blades. Repeat the finger sweeps. If the object is still not dislodged, repeat steps 1 through 4 until the object is dislodged.

5. Ventilation: Once the object is dislodged, check for breathing and heart rate; administer artificial respiration and CPR if necessary. When the dog revives, proceed to the animal hospital for further treatment.

Laryngospasm (Reverse Sneezing)

This uncommon condition can be alarming because it sounds as if the dog can't catch his breath. During an attack, the dog produces a loud snorting noise caused by violent attempts to draw in air. this may occur several times in succession after the attack, the dog appears completely normal. Reverse sneezing is believed to be caused by a temporary spasm of the muscles of the larynx, possibly the result of a drop of mucus that falls on the vocal cords from the soft palate. The attack can be ended by making the dog swallow. This is accomplished by massaging the front of the neck in the region of the pharynx just beneath the jaw. Alternatively, place your hand over the dog's nostrils for an instant. If the attack does not stop and the dog collapses, suspect a foreign body in the larynx. Reverse sneezing is commonly seen in Corgis and Beagles.

Laryngeal Paralysis (Vocal Cord Paralysis)

This is an acquired disease that occurs in older dogs of the large and giant breeds, particularly Labrador Retrievers, Golden Retrievers, Irish Setters, St. Bernards and Great Pyrenees. In Siberian Huskies, Bouviers des Flandres, Bull Terriers, and Dalmatians it occurs as a hereditary defect. In these breeds, dogs with this problem should not be bred. Laryngeal paralysis results from damage to the nerves that control the movement of the larynx. Trauma and age may be factors. Hypothyroidism may also contribute to this problem. A classic sign of laryngeal paralysis is a characteristic croupy or "roaring" noise heard as the dog inhales. Initially it appears during or after exercise. Later it occurs at rest. Another sign is progressive weakening of the bark, which ends in a croaky whisper. In time the dog develops noisy breathing, labored breathing, reduced exercise tolerance, and fainting spells. Laryngeal edema may develop and further compromise the airway, causing respiratory collapse and even death. The diagnosis is made by examining the vocal cords with a laryngoscope. Paralyzed vocal cords come together in the middle instead of remaining well apart. This produces an tight air passage through the larynx.

Laryngeal Trauma

Choke chain injuries, tight slip collars, or any rope around the neck can fracture the hyoid bone and/or cause compression damage to the nerves of the pharynx and larynx. Other causes of trauma to the larynx include bite wounds and sharp foreign objects such as bones and pins that penetrate the larynx. Dogs with laryngeal injuries often breathe normally at rest but show respiratory distress during exertion.

Laryngeal Collapse

This is a late stage in airway obstruction. Pressure changes in the upper airway caused by stenotic nares, an elongated soft palate, laryngeal paralysis or everted laryngeal saccules stretch the ligaments that support the laryngeal cartilages. These cartilages gradually collapse inward and block the airway. At this stage any change in the dog's need for air can cause acute respiratory insufficiency and cardiac arrest.

Debarking and Barking Problems

Some dogs simply seem to enjoy barking. But constant shrill barking can lead to problems with neighbors and a dog being dropped off at the local shelter. Debarking surgery removes some of the vocal cord tissue. This can be done through the mouth or through the throat. Lasers are sometimes used for this surgery (not recommended). After debarking, dogs can still bark but it is a quieter, hoarse sound. If the dog develops scar tissue, he may recover the ability to bark normally. Too much scar tissue may interfere with breathing. Postoperative care is important, because any swelling in this area could possibly cause acute breathing problems. You may need to search for a doggy doctor experienced with this surgery. Before doing debarking surgery, you should try behavior training and/or eliminate the cause of the excessive barking.

Coughing

Coughing is a reflex initiated by an irritation in the airway. Coughs are caused by respiratory infections, congestive heart failure, chronic bronchitis, respiratory tract tumors, collapsing trachea, pressure from tight collars and inhaled irritants such as grass seeds, fumes and food particles. Coughs are self-perpetuating. Coughing dries out the mucous membranes and irritates the breathing tubes-leading to further coughing.

Diagnosing a Cough

The type of cough often suggests the diagnosis:

A deep, dry, hacking cough made worse by exercise 

or excitement is characteristic of kennel cough.

A moist, bubbling cough indicates fluid or phlegm in 

the lungs and suggests pneumonia.

A high, weak, gagging cough, followed by swallowing 

and licking the lips, is characteristic of tonsillitis and 

sore throat.

A spasm of prolonged coughing that occurs at night 

or while lying on the sternum suggests heart disease 

A "goose-honk' cough in a toy breed dog indicates a  

collapsing trachea. 

The diagnostic workup of a dog with a chronic cough includes a chest X-ray and transtracheal washings. washings are cells obtained by flushing the trachea with saline solution. This can be done with a sterile tube passed down the trachea while the dog is sedated, or by direct penetration of the trachea through the skin of the neck using a needle and catheter. The washings are processed for cytology and bacterial culture. The information usually leads to a specific diagnosis.  Bronchscopy is particularly useful in the investigation of chronic coughs and coughs with the production of mucus and blood. The procedure requires sedation or general anesthesia. A rigid or flexible endoscope is passed into the trachea and bronchi. This enables the trained professional to see the interior of the respiratory tract. Biopsies can be taken with accuracy, and washings collected for examination and culture. bronchoscopy is also the procedure of choice for removing bronchial foreign bodies.

Trachea and Bronchi

Acute Tracheobronchitis (Kennel Cough Complex)

The kennel cough complex is a group of highly contagious respiratory diseases in dogs. The name comes from the fact that the infection tends to spread rapidly, especially among dogs in boarding kennels or dogs who have been to places where large number of dogs congregate, including dog shows and dog parks. Several viruses and bacteria, alone or in combination, can cause the disease. The organisms most frequently involved in canine parainfluenza virus and the bacteria Bordella bronchiseptica. Canine adenovirus types CAV-1 and CAV-2, as well as canine herpesvirus, canine distemper and mycoplasma, are other causes of kennel cough. A harsh, dry, hacking cough is the characteristic sign of tracheobronhitis. The cough is unproductive and is often accompanied by gagging and retching. Except for the cough, the dog is bright and alert and has a good appetite and a normal temperature. In most cases kennel cough is a mild disease. With rest and a stress-free environment, most adult dogs recover completely in 7 to 14 days. Keeping the dog quiet will speed up recovery. Kennel cough may be complicated by secondary bacterial pneumonia. This is most likely to occur in dogs with bronhitis, collapsing trachea or diseases that lower their resistance to infection. In puppies, kennel cough can be accompanied by nasal congestion. These puppies require frequent care to loosen thick secretions, improving breathing and prevent pneumonia. This is also true for toy breeds. A severe form of tracheobronchitis that can lead to pneumonia is characterized by low-grade fluctuating fever, loss of appetite and depression.. These dogs have a moist productive cough, nasal discharge, exercise intolerance, wheezing and rapid breathing. This form of kennel cough requires hospitalization.