Glendale Animal Hospital - The Family Veterinarian


The respiratory system consists of the lungs and all related structures that serve to facilitate movement of air into and out of the lungs. These include the larynx, trachea, bronchi and diaphragm. The nose, sinuses and oral cavity are also considered part of this system. As the muscles of the chest and diaphragm contract, the chest cavity expands and air is sucked into the lungs. As these muscles relax and the chest cavity collapses, air is pushed back out of the lungs.

The purpose of the respiratory system is primarily to bring oxygen to the circulatory system and remove carbon dioxide and some other wastes from the blood. Filtration of airborne contaminants could also be considered a function of these organs. It is, therefore, reasonable to state that proper health of this system is essential to the overall health of the patient.


This is probably the most common respiratory problem of dogs as well as the most contagious. Dogs will obtain the infection via inhalation of any number of infectious organisms and may be ill for a few days up to a few weeks. While many, less-common organisms can be involved in this type of infection, bordatella, adenovirus, parainfluenza, along with herpesviruses, reoviruses, various types of bacteria and mycoplasma organisms are all commonly implicated. It is no wonder that this is often referred to as a "mixed" infection. On occasion the canine distemper virus may be involved in a more serious version of this disease.

Clinical signs include a dry, harsh, honking or hacking cough that seems to occur in repeated episodes during the day. Usually the cough is non-productive, meaning that little flem is expectorated by the pet. Most dog owners will tell the vet they are concerned about something being stuck in the dog's throat; usually the cough can be triggered by gently rubbing the dog's windpipe. Dogs are typically alert, without a fever and normal otherwise. Left untreated, however, more severe infections of the eyes, nose and lungs may develop and can even result in death.

Although cases will heal without treatment, most dogs are treated for their comfort and to guard against the more serious consequences which could arise. Also, despite being called "kennel cough", dogs do not need to be kenneled to contract this condition as exposure can occur through the air, even in backyard dogs. Diagnosis is based on history, clinical signs, X-rays, throat cultures and blood counts.


Dogs should be kept in a dry, warm, draft-free environment. Exercise should be avoided until the condition subsides. Antibiotics, anti-inflammatory medication and cough suppressants are all commonly employed. Dogs with more serious symptoms may need nebulization therapy and even hospital care. Vaccinations are available to prevent the more serious forms of the disease from happening, but not all of these infections will be preventable due to the complex nature of the disease. Dogs placed in kennels or other crowded environments should be given a bordatella vaccination as a precaution.



Rhinitis, by definition, is inflammation of the nasal cavity. Most cases are caused by some offending organism or substance such as bacteria, viruses or fungi. However, foreign objects such as foxtails, trauma to the nose, allergies, sinus conditions, tumors and infections of the teeth can also lead to this condition. While the diagnosis of rhinitis may not be complicated, determining the exact cause can be more involved.

Clinical signs include sneezing, a nasal discharge which may be thin and clear or thicker and yellow to greenish, blood in the discharges or during sneezing, unusual swelling around the nose or face, difficulty breathing, pain when eating, associated conjunctivitis, fever, loss of appetite and lethargy in more severe cases. Diagnosis is based on history, clinical signs, blood counts and serum chemistries, X-rays, cytology of exudates, cultures, endoscopy and special serological testing where warranted.


Here again, diagnosis is so important as the treatment will vary greatly depending on the cause of the rhinitis. Foreign objects will require removal under sedation/anesthesia. Lesser infections and allergies will respond well with antibiotics and steroids or antihistamines. Tumors will require major surgery. Sometimes flushing or "scraping" the nasal cavity will be needed in more severe or less responsive cases.



All dogs bred for that "pushed in" facial appearance may have some or all the components of this condition. In short, dogs of these breeds have congenital defects that can restrict air from flowing smoothly through the respiratory system.

STENOTIC NARES, wherein the nose will have little or none of its normal opening. ((Stenotic Nares))

OVERLONG SOFT PALATE, where the roof of the mouth (palate) overhangs the epiglottis. (part of the larynx)

EVERTED LARYNGEAL SACCULES which are actually contained within the voice box; these tissues protrude excessively and may be more secondary to the overall condition and not a congenital defect.

Besides these primary defects, these breeds may also have enlarged tonsils, swollen tissues in the back of the throat, and collapse of the trachea. In part or together these irregularities produce upper airway restrictions and clinically result in trouble breathing, loud noises during breathing including gurgling, snoring, coughing, a decreased ability to exercise, an increased susceptibility to heat stroke, gagging, trouble swallowing and changes in the bark.

Diagnosis is based on history, clinical signs and physical examination. X-rays may be helpful to further define the extent of the problem. Direct examination with endoscopic type instruments will also help the veterinarian visualize the defects.


Most dogs can be helped greatly by surgical correction (improvement) of the defects present. This usually requires "wedge resection", removing part of the nose to increase the opening thereof, removal of some of the excessive soft palate, and in some cases, removal of the everted saccule. While the word cure would not be appropriate, most dogs do much better after this type of treatment.



A cleft palate and cleft lip occurs when the roof of the mouth and/or lips fail to close and fuse during the formation of the pup; the nasal cavity and oral cavity will then abnormally communicate. This is considered a congenital defect and will generally result in milk (or solid food if the dog survives to this stage) irritating the nasal cavity causing rhinitis, sinusitis or worse, milk being inhaled causing the very serious condition aspiration pneumonia. Diagnosis is based on clinical signs and physical exam. ((Cleft Palate))


Treatment for this condition is always surgical and large defects are difficult and costly to close. Smaller defects may be more easily repaired although more that one surgery is sometimes required. Left untreated, most dogs die of complications so euthanasia may be considered. For repair, a surgeon experienced in this type of surgery should be selected.


Sinusitis is inflammation of the sinus cavities, which lie behind the front facial bones of the dog. Most cases are caused by some offending organism or substance such as bacteria, viruses or fungi. However, foreign objects such as foxtails, trauma to the head, allergies, nasal conditions, tumors and infections of the teeth can lead to this problem. Many cases of sinusitis occur along with cases of rhinitis; determining the exact cause is very important for proper treatment.

Clinical signs include sneezing, a nasal discharge which may be thin and clear or thicker and yellow to greenish, blood in the discharges or during sneezing, unusual swelling around the nose or face, difficulty breathing, pain when eating, associated conjunctivitis, fever, loss of appetite and lethargy in more severe cases. Dogs may have a "reverse sneeze", which is usually the sound made as the dog gags on and swallows sinus discharges. Diagnosis is based on history, clinical signs, blood counts, serum chemistries, X-rays, cytology of exudates, cultures, endoscopy and special serological testing where warranted.


Diagnosis is so important as the treatment will vary greatly depending on the cause of the sinusitis. Foreign objects will require removal under sedation/anesthesia. Lesser infections and allergies will respond well with antibiotics and steroids or antihistamines. Tumors will require major surgery. Sometimes flushing the sinuses will be needed in more severe or less responsive cases.



Trauma to the larynx, viral/bacterial infections, heat stroke, excitement and excessive barking can all lead to inflammation and swelling of the larynx. Clinical signs include a change in the voice (hoarse barking), cough, soreness to the throat, trouble swallowing, trouble breathing including gurgling or a noisy respiration. Diagnosis is based on history and clinical signs.


Most dogs with laryngitis are easily treated with the proper medications. Dogs that are easily excited or constant barkers will often have recurrent episodes of laryngitis. Injections of cortisone, cough suppressants, tranquilizers and ice packs applied to the throat are all effective. Antibiotics may be needed in cases of infection.


A rare condition of older and larger dogs whereby the nerves that control the larynx do not function properly and the aryteniod cartilages and vocal cords tend to "lean" inward and restrict airflow. Most dogs with this condition will have symptoms of a roaring-like sound during breathing, made worse with exercise. Some dogs may also have trouble swallowing. Diagnosis is based on physical examination, history, size of dog, X-rays and endoscopy. Some dogs may have associated hypothyroidism or polyneuropathy, which should be investigated as well.


Any underlying, systemic disease should be treated first. Otherwise, several surgical techniques can be used including removal of the vocal cords and partial removal of the arytenoid cartilages, surgical fixation of the arytenoid cartilage, or more complicated re-arrangement of laryngeal muscles to restore partial function can be attempted.



Many small breed dogs, including but not limited to short-nosed varieties suffer from variations of this condition. Briefly, the trachea or main "wind-pipe" in the throat will partially collapse, often under mild excitement or exercise, creating an airway obstruction, which produces signs of episodic coughing and hacking by the dog.

While the exact cause is poorly understood, there seems to be some degree of weakness inherent in the cartilage which makes up the rings of the trachea. The condition which often gets worse with age can be made worse by obesity, other chronic respiratory conditions, being tugged upon by the collar and heart disease which leads to fluid accumulation in the lungs. Diagnosis is based on history, clinical signs and X-rays. ((Tracheal Collapse))


Most dogs never need more than a gentle throat rub and a few soothing words to handle this condition. While there is a surgery available to help correct the collapse, this author has never seen a dog with severe enough symptoms to warrant its use. For dogs with the condition, use a harness rather than a collar for walks, keep the pet's weight under control, treat any other problems such as bronchitis; there then should not be any long term consequences of the condition. In some instances medications to dilate the windpipe or mild sedatives prove useful.


Bronchitis is inflammation of the bronchi, the large and small windpipes that carry air into and out of the lung tissues. Chronic bronchitis occurs when the condition results in permanent changes to these structures including thickening and loss of elasticity to the bronchi. The term Tracheobronchitis infers that the trachea and the bronchi are all involved in the inflammatory process. Tracheitis occurs when only the trachea is involved, but this author feels that tracheitis rarely occurs without concurrent bronchiolar involvement. ((Bronchi))

While the symptoms of bronchitis are similar, the causes of bronchitis are numerous. These include bacteria, viruses, allergic reactions, passive smoke inhalation, heart disease, endocrine disorders, dust and air pollution. Clinical signs always include coughing, which may or may not be productive, wheezing when breathing, shortness of breath, fever, nasal discharge and generalized difficulty breathing. Dogs with chronic bronchitis, therefore, seem to have bouts of coughing continually. Most dogs with bronchitis are also overweight, which certainly worsens the condition.

Diagnosis is based on the history of coughing, physical examination, blood counts, X-rays, endoscopy and analysis of secretions obtained by what is called a tracheal wash biopsy. Without testing it is difficult to determine the cause based on the symptoms alone. Other testing if heart or endocrine disorders are suspected may also be needed.


Dogs with bacterial bronchitis or viral bronchitis with secondary bacterial involvement will be treated with antibiotics, cough suppressants in more extreme cases, medications to open breathing passages and sometimes nebulization therapy (like concentrated vaporization of medications which are then inhaled).

Dogs with allergic bronchitis are treated with cortisone like drugs, antihistamines, medications to dilate breathing passages (bronchodilators) and in extreme cases oxygen and nebulization treatments.

Other cases, including chronic bronchitis but not including cases with bronchiolar disease secondary to other problems, cortisone-like drugs, medications to open the air passages, antibiotics, expectorants and cough suppressants are all utilized. Dog owners should realize that a cure is unrealistic and a minimum amount of coughing will be acceptable. Overweight dogs should be checked for metabolic diseases and put on a supervised weight loss program as soon as possible.



Pneumonia is inflammation of the main body of lung tissue; it is sometimes referred to as Pneumonitis. Infectious pneumonia would then be caused by bacteria, viruses or mycoplasma organisms. Your veterinarian may use other terms to indicate similar conditions including Lobar Pneumonia, when the infection is confined to one lung lobe (area) only; or Bronchopneumonia, when the air passages are also involved.

Dogs may get this disease in various ways, including airborne inhalation of pathogens, spread of infection from the nose or sinuses, from penetrating wounds, foreign objects entering the lungs and the spreading of other infections through the blood into the lung tissues. Inflammation may occur before infection actually sets in. ((Pneumonia))

Symptoms of this type of pneumonia include coughing, rapid respiration, trouble breathing, fever, weight loss, loss of appetite, and lethargy. Diagnosis is made from physical examination, blood counts, X-rays, cytologic examination and culture of exudates and in some instances biopsy of lung tissue. History is important if fungal infection is suspected.


After an accurate diagnosis including a culture is obtained antibiotic therapy is most important. As a culture may take several days, therapy may need to be started with the most reasonable antibiotic being selected. IV fluids, oxygen and nebulization therapy and general supportive care are all important for more critical patients.



Many of the systemic fungal organisms cause a form of pneumonia. While some infections exhibit few if any symptoms, most dogs will show symptoms of coughing, fever, swollen lymph nodes, trouble breathing, wheezing and crackling sounds heard when the dog breathes, and possibly lameness and diarrhea. Some dogs will also have rhinitis and sinusitis. Diagnosis is based on history and geographical area the dog is/has lived in, physical examination, X-rays, blood count and serum chemistries and special tests for suspected fungi.





Inhalation of any material other than air will constitute aspiration, after which a secondary inflammatory process will ensue. Commonly vomit, dusts, smoke, oral secretions, water if near drowning and foreign objects like foxtails or other plant materials can all become aspirated. These substances, when inhaled, damage the lung tissue and lead to inflammation, possibly infection, and overall the disruption of normal air exchange between lung tissue and the blood supply. If the amount of foreign material is large enough, as in a near drowning, the dog may immediately suffocate.

Clinical signs of aspiration pneumonia include trouble breathing, which may be severe, cough, weakness, gagging or choking, blue lips or gums, noise upon breathing, fever, depression and loss of appetite. Some dogs may develop pleuritis or pyothorax if the insult was some type of foreign object. Diagnosis is based on history, physical exam, blood counts, serum chemistries, X-rays, cytology and culture of material from the lungs.


Removal and clearance of as much material from the lungs is a first priority. Secondly, prevention of further aspiration may also be needed, especially in cases of vomiting. Hospitalization with oxygen therapy, mechanical respiration in extreme cases, antibiotics and anti-inflammatory medications are all important. IV fluids and nutritional support may be necessary, and most patients who survive a few days will survive. Repeat chest X-rays can be used to determine the degree of healing and if secondary complications are occurring.



PIE is a rare condition where lung tissue becomes infiltrated (filled) with a type of white blood cell called an eosinophil. The cause is poorly understood and in some ways mimics allergic-type reactions. Nevertheless, a connection to allergic disease has also not been established. Clinical signs include coughing, trouble breathing, fever, weight loss and rapid respiration. Diagnosis is based on physical examination, X-rays, blood counts, serum biochemical analysis and analysis of tracheal secretions. Several other diseases may produce eosinophils in lung tissue, and these should always be considered first. These include heartworm disease, fungal infections and other lung parasites.


Most dogs will respond quickly and dramatically to the use of cortisone type medications. Many pets will go into remission after 3-5 weeks of tapering therapy although relapses are possible. If parasites are present, these will also require treatment. Secondary infectious pneumonia can also occur, which then would necessitate antibiotic therapy.



Sometimes when checking the lungs via X-rays, singular type masses may be found. Many dogs have lung lesions without any clinical symptoms. Other times, the masses are found during the investigation of lung disease. Depending on the type of mass(es) and their location, airflow through the lungs may be disrupted, secondary pleuritis may occur or a more generalized infection can set in. ((Solitary Lung Mass))

The types of masses encountered include the following; Bullae: large air-filled pockets often created from damaged lung tissues; Cysts: which are often congenital defects or developmental defects; Abscesses: which are collections of infectious materials and may represent a localized pneumonia process; Granulomas: which are similar to abscesses but are more solidified and contain scar tissue; and Parasitic Granulomas: which are granulomas caused by lung parasites.

If clinical signs are present, they may include a cough, which may or may not be productive and in some cases may include blood in the exudates, trouble breathing, fever, decreased exercise capacity, lethargy and poor appetite. Diagnosis is generally made based on the clinical signs and chest X-ray, with definitive diagnosis occurring via a biopsy. Secretions analyzed may, however provide a clue to the problem.


Treatment here will depend upon the nature of the mass and the degree to which it affects the dog. Cysts or bullae require no treatment in most cases. Walled off abscesses or fungal granulomas will require antibiotic or anti-fungal medications. Parasitic granulomas would benefit from anti-parasitic medications. Some masses, including rare, solitary tumors will require surgical removal of the lung lobe affected.



Pulmonary edema is actually not one specific disease but a result of other abnormalities, which causes a build-up of fluid in the lung tissue. Fluid collecting in the lungs, then, is termed pulmonary edema. Fluid in the tissues obstructs the normal exchange of oxygen, carbon dioxide and other waste products in the lungs.

The causes of pulmonary edema are numerous: congestive heart failure, excess IV fluids given to a patient, neurologic disease, shock, aspiration pneumonia, (near) drowning, smoke or chemical inhalation, pancreatitis, kidney failure, snake bite, poisoning, electric shock, seizures, traumatic injuries, liver diseases and low protein in the blood.

Clinical signs include difficulty breathing, coughing, weakness or inability to exercise, restlessness and possibly blueness to the gums and lips. The severity of symptoms will depend upon the amount of fluids in the lungs. Diagnosis will be based on history, physical examination, EKG analysis, blood counts, serum chemistries, urinalysis, fecal examination X-rays and other specific tests as warranted. Severe cases need immediate treatment as suffocation and death can occur. ((Pulmonary Edema))


Dogs with this condition need immediate help getting oxygen, followed by getting fluid removed from the lungs and the cause determined and eliminated if possible. Oxygen therapy, including mechanical respiration in severe cases is most important. Diuretics are used to remove fluids. After appropriate testing, the specific cause is then treated.



This condition is characterized by widespread lung damage and is often associated with pulmonary edema; always associated with some other generalized illness or condition. Infections, shock, aspiration pneumonia, trauma, transfusions, burns, smoke/poison inhalation, pancreatitis, and surgery can all lead to acute (sudden) lung damage and respiratory failure.

Clinical signs include sudden trouble breathing, even to the extent of severe respiratory distress, hyperventilation, restlessness, wheezing or otherwise noisy respiration and a rapid heart rate. Diagnosis is made in lieu of other conditions based on history, physical examination, X-rays, blood counts, serum chemistries and blood gas analysis where available.


As in other similar circumstances, the underlying or primary disorder must be addressed. Oxygen therapy including artificial respiration may be needed and often is poorly effective. Careful fluid therapy may be used, and cortisone or diuretics are used but are of questionable benefit. Treating the main problem and keeping the dog alive will yield the best results.



Certain parasites may inhabit or pass through the lungs as part of their life cycle. In doing so, tissue damage and obstruction of airflow results in lung disease. In other cases allergic type reactions occur in the tissues. Clinical signs of lung parasites include coughing, trouble breathing, occasional fever, weight loss and poor general condition. Diagnosis is based on history, area of residence, physical examination, fecal analysis, X-rays, blood counts and endoscopy.

The following parasites are known to inhabit or pass through the lungs:

Paragonimus kellicotti: often causes solitary lesions.

Toxoplasma gondii: the cause of toxoplasmosis.

Ancylostoma spp.: the dog hookworm.

Toxacara spp.: the dog roundworm.

Dirofilaria immitis: the cause of heartworm disease.

Filaroides spp.: contacted by ingestion of feces or other contaminants.

Pneumocystis carinii: received by eating rodents.

Aleurostrongylus abstrusus: from eating lizards or birds.

Capillaria aerophila: from ingestion of infected material.


Various antiparasitic drugs work well to kill most of these parasites. Sulfa drugs are often used to deal with Pneumocystis infections or secondary pneumonia caused by these parasites. In some cases, worms may need to be pulled manually from the bronchi. Cortisone and other medications may be needed to treat inflammation and related problems.



Pneumothorax describes a condition where outside air has entered the chest cavity and now resides between the lungs and the chest wall, and thusly, the amount of lung volume is decreased as lung tissue collapses. There are three main types of pneumothorax described:

Open Pneumothorax, where a patent hole exists between the outside air and the chest cavity.

Closed Pneumothorax, where air is in the chest but there is no communication to the outside.

Tension Pneumothorax, which is like a one way valve where more air can come into the chest but cannot escape. These cases get worse rapidly and death will occur unless very prompt treatment is instituted.

The most common cause of pneumothorax is traumatic injury that produces a chest wound or airway damage. Rupture of lung cysts, lung parasites and surgical procedures can also cause the condition. The severity will depend on how much air enters the chest as this produces a relative collapse of lung tissues. Clinical signs include rapid respiration which may be quite shallow, weakness or inability to exercise normally, severe trouble breathing in some cases, blue gums, difficulty getting comfortable, and death. Diagnosis is based on history, physical examination, X-rays, heartworm testing, fecal analysis and endoscopy.


Very mild cases require little or no treatment. Wounds should be covered and closed. Placing a needle into areas of the chest and removing air one or more times often works well. Sometimes, if air continues to get into the chest, a tube may need to be surgically placed in the chest to continually remove the air via some type of suction. In some cases major surgery is needed to close the cause of the air leakage. Oxygen therapy will also be helpful in most cases. As most cases are caused by traumatic injuries, other wounds are likely present and the treatment of pneumothorax will be a part of a generalized treatment plan.



Pleural effusions occur when some type of liquid material collects between the chest wall and around the lungs causing collapse of the lung tissues and inhibition of normal respiration. The type of fluid would then depend on the cause of the process by which fluid is produced. These effusions are classified depending on their characteristics: Transudates, Modified Transudates, Exudates, Neoplastic, Chylous and Hemorrhagic.

Transudates are generally thin watery fluids with few cells as part of the mix. The causes of transudative fluids include congestive heart failure, hepatic disease, low blood protein due to kidney disease or intestinal disease and thromboembolism.

Modified Transudates usually occur when lymphatic drainage is obstructed and fluids cannot normally leave the chest. Greater cell numbers are usually present in these fluids. The cause of this type of fluid accumulation includes congestive heart failure, twisting of lung lobes, neoplasia of the lungs or chest and diaphragmatic hernia.

Exudates are generally thick and secondary to some type of inflammatory process that can include infection. Chest wounds, foreign objects getting into the chest and infections which spread from the lungs or other areas often cause septic exudates, which means bacterial infection is present. The other term for this problem is Pyothorax. Non-infectious exudates are uncommon.

Tumors in the lungs or chest cavity can produce fluids known as Neoplastic Effusion. This type of fluid will contain numerous cancer cells. If a lymphatic duct ruptures, lymph fluid, known as chyle, can leak into the chest cavity. This then produces a Chylothorax; a thick, white, milky fluid will be present. This condition may occur secondary to trauma, spontaneously, or secondary to internal tumors. Finally, blood may fill the chest cavity and produce a Hemorrhagic Effusion. Often, some severe thoracic trauma will cause this type of effusion, but rupture of certain types of tumors or clotting disorders can also produce this internal hemorrhage.

The symptoms of pleural effusions will vary with the cause, the amount of fluid in the chest, and the duration of the illness. Mild disease will be hard to detect. More severe illness will produce nebulous pain, trouble breathing, blue gums, open-mouth breathing, weight loss, lethargy and loss of appetite. Cough and swelling of the abdomen can occur in some cases. Diagnosis depends on historical information, physical findings, X-rays, blood counts, serum chemical analysis and analysis of fluid removed from the chest cavity including cultures and cytology.


As with other conditions, treatment of the primary cause (such as heart or liver disease) would be of first priority. In some cases, fluid may be suctioned directly from the chest. Other dogs will require a chest tube or tubes placed surgically to remove fluid and instill medications. In still other cases, surgery of the thorax will be needed to remove tumors, repair defects or eliminate foreign objects. Treatment is often difficult but can be effective if the primary cause is identified and properly addressed.