Pressure is applied to it when you breath in and out. As long as the straw stays strong, airflow is unrestricted. However, once it collapses in an area, it is permanently weakened and it collapses more easily and more often thereafter. This condition normally occurs in older dogs, although it can occur in young dogs. The initial signs are usually a mild cough during exercise, excitement, and stress.
Cervical collapse occurs during inhalation and intrathoracic collapse occurs during exhalation.
It is also possible for the collapse to occur in both places simultaneously. Both are characterized by a classic honking cough, often called a goose honk cough. A grading system to document the severity of the collapse was devised by Drs. Tangner and Hobson for use in determining the best way to treat the collapse. Dogs with a Grade I or II collapse are usually good candidates for medical management of the condition.