A varying flora of indigenous commensal organisms (including Pasteurella multocida, Bordetella bronchiseptica, streptococci, staphylococci, pseudomonads, and coliform bacteria) normally reside in the nasal passages, nasopharynx, and upper trachea, and at least intermittently in the lungs of dogs and cats, without causing clinical signs. Opportunistic infections by these bacteria may occur when respiratory defense mechanisms are compromised by infection with a primary pathogen (eg, distemper Canine Distemper Canine distemper is a highly infectious, systemic, viral disease of dogs that occurs worldwide. Dogs commonly exhibit systemic clinical signs (fever, lethargy, loss of appetite), respiratory... read more , parainfluenza virus Kennel Cough Kennel cough results from inflammation of the trachea. It is a mild, self-limiting disease but may progress to bronchopneumonia in puppies or to chronic bronchitis in debilitated adult or aged... read more , or canine type 2 adenovirus in dogs, and rhinotracheitis virus or calicivirus Feline Respiratory Disease Complex Feline respiratory disease complex is typically manifested by clinical signs of the eyes, nose, and mouth ( rhinosinusitis, sneezing, conjunctivitis, lacrimation, salivation, and oral ulcerations... read more in cats), other insults (eg, inhalation of smoke or noxious gases), or diseases such as congestive heart failure Heart Failure in Dogs and Cats The three primary functions of the cardiovascular system are to maintain 1) normal blood pressure and 2) normal cardiac output, both at a 3) normal venous/capillary pressure. Heart failure is... read more and pulmonary neoplasia Neoplasia of the Respiratory System in Dogs and Cats Nasal lymphoma involving the left nasal cavity. There is breach of the left orbital wall with tumor extension into the left orbital region. The left eye is deviated craniolaterally. The tumor... read more .
Secondary bacterial infections complicate the management of viral respiratory infections of both dogs and cats. Pathogens may continue to reside in the respiratory tract of convalescent animals. When stressed, these animals may relapse; they can also act as a source of infection for others. Poor management practices (eg, overcrowding) are often associated with poor hygienic and environmental conditions, and the resultant stress increases both the incidence and severity of infections. Conditions that favor the spread of infections often occur in catteries, kennels, pet shops, boarding facilities, and humane shelters.
Congenital abnormalities, such as stenotic nares, elongation of the soft palate, nasopharyngeal turbinates, and tracheal stenosis, can cause respiratory dysfunction. Neoplastic masses, degenerative changes of the airways, and tracheal collapse can result in dyspnea and other clinical manifestations of respiratory disease.
Tracheal collapse is most common in toy and miniature breeds of dogs. Yorkshire terriers are ½ to ⅔ of reported cases; this condition is rare in cats and large- or giant-breed dogs. Tracheal collapse is characterized by weakened cartilage rings, with dorsoventral flattening of the trachea, restricting airflow. The cause is multifactorial.
Affected animals have a nonproductive, honking, chronic cough and increased inspiratory effort, with extrathoracic tracheal collapse or increased expiratory effort with intrathoracic tracheal collapse. Thoracic radiographs may show evidence of the collapse. Fluoroscopy is a noninvasive way to identify the location of collapse and determine whether the collapse is dynamic. Bronchoscopy may assist with fluid collection for cytology and culture if there is a secondary bacterial infection. Signs worsen with an increase in heat, excitement, and after exercise. Dogs may have concurrent pulmonary disease (eg, chronic bronchitis Kennel Cough Kennel cough results from inflammation of the trachea. It is a mild, self-limiting disease but may progress to bronchopneumonia in puppies or to chronic bronchitis in debilitated adult or aged... read more , laryngeal paralysis Laryngeal Paralysis in Dogs and Cats Laryngeal paralysis is common in dogs and rare in cats. Signs include: dry cough voice changes noisy breathing that progresses to marked difficulty in breathing with stress and exertion stridor read more , bronchomalacia, or pneumonia Pneumonia in Dogs and Cats Pneumonia is an inflammation of the pulmonary parenchyma that results in respiratory disturbance. It can be caused by a variety of organisms, including viruses, bacteria, fungi, parasites, and... read more ). Treatment centers around managing the clinical signs with antitussives, antibiotics, corticosteroids with or without bronchodilators, as well as weight loss, exercise restriction, and reduction of excitement and stress.
If medical management fails, intraluminal tracheal stenting may be considered. Stents can be placed with fluoroscopic and/or endoscopic guidance. Surgical placement of external tracheal rings can be attempted with implant failure as one complication. Neither treatment will eliminate the clinical signs completely and are considered "salvage" procedures.
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Also see pet health content regarding lung and airway disorders in dogs Introduction to Lung and Airway Disorders of Dogs The respiratory system consists of the large and small airways and the lungs. When a dog breathes air in through its nose or mouth, the air travels down the trachea, which divides into the tubes... read more and cats Introduction to Lung and Airway Disorders of Cats The respiratory system consists of the large and small airways and the lungs. When a cat breathes air in through its nose or mouth, the air travels down the trachea, which divides into the tubes... read more .