The tracheal anatomy is supported by C-shaped rings of cartilage that are subject to degeneration and collapse. The flaccid trachea changes diameter with different phases of breathing which frequently elicits a dry cough, especially repeated cycles of episodic cough. The coughing is frequently exacerbated by tugging on the leash or by irritants in the air, such as perfumes, smokes or powders. While the underlying anatomic problem cannot be corrected, there are medical and surgical strategies to minimize the cough and respiratory obstruction that is produced. Harsh noises are more often associated with airway problems than with lung or cardiac problems.
Coughs occurring because of allergic or cancerous conditions are frequently dry and nonproductive.
Dogs with bacterial pneumonia will usually have a soft, productive cough that reflects the presence of mucus and purulent material within the airways. The productive nature of a cough can be difficult to ascertain because most dogs will swallow the material that is coughed up. An astute owner may note that the dog swallows or retches after coughing. Patients with pneumonia frequently are systemically ill, with fever, poor appetite and lethargy, as well as cough, nasal discharge, and varying degrees of respiratory distress. Pulmonary vascular disease associated with arterial blood clots may result in the coughing of blood, a condition termed hemoptysis.